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1970 Gto Trunk pan Help!

10K views 11 replies 8 participants last post by  a1cnc 
#1 ·
Hey Guys,

New to the forum and first time posting. I tried the search function with no luck. I am in the process of restoring a 1970 Gto and currently replacing the trunk pan. I ordered a 1 piece from AMD and was told it fits a 68-70. Well im having problems. I spliced in the rear tail panel bumper/body mount support bracket as AMD says is needed for a 70. None of the indentations on the pan line up with the bumper support and my rear tail panel wont line up with the trunk pan. Does any one have any suggestions or have gone through this? The stock pan kind of has a 2 step raise to the rear of the tail panel where the 68-69 does not. It looks like a 70 Chevelle tail pan is a closer fit to what I need but its not listed to fit the gto. I already cut the pan up so I can't return it. Any help is appreciated Thanks guys

John
 

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#2 ·
It would help if you sent pics of your project and the problem. As far as I know, the trunk pans should be the same. I cut one out of a 1970 Grand Prix and was going to use it in my '68 Lemans. Same general floor pan, but the area I think you are talking about is indeed different. So my thinking was to use the pan and splice it near the top at the area below the trunk lock bracket that the trunk locks to.

So if you can, provide some good pics and someone may be able to help. :thumbsup:
 
#3 ·
Thanks Jim! Here are a few pictures of my new pan and old pan. Wish When I cut the old one out I would have kept that piece now..Rookie mistake. You are correct they are indeed different where the trunk latch attaches. I believe I will have to graft in a new piece there. Was hoping there was some magical answer to avoid that lol. My question is does anyone know which models use that same step up in the rear to the latch?

Thanks for the help,

John
 

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#4 ·
Yep, the pan appears to be the same, but that "rear shelf" is the difference. I suspect that 1970-72 would all be the same, but member Pinion head is the expert on these years with regards to bodies and can give you a much better answer. Hopefully he will see your post or you could PM him directly with your question.

An option might be to take a section or template to a metal fab shop and let them bend you up a piece that could work, or at least take care of a large section of it. This is where fab work & skills come into play. :thumbsup:
 
#6 ·
With all the up & down temperature swings have been working every minute outside when it's near 50 degrees & warmer. 62 today :). Will clear out more PM room tonight.

On the one piece trunk pans, the following is what I was told again late this Fall, in regards to one piece trunk pans. This was from long time bodyman who has a TON of hands on high quality experience replacing rear sheetmetal under '68-72 GM A-body's. "As far as reproduction one piece trunk pans go, there is a '68-69 LeMans/GTO one piece trunk pan and there is is a '70 Chevelle one piece trunk pan". Several of us have the confirmed viw after a lot of examination that neither one piece trunk pan is a 100% install into a '70 LeMans/GTO or a '71-72 LeMans/GTO (or a 442, for that matter). The differences are in regard to the furthest rear stamping, ESP the stamping as to how it is shaped on each side where the back of the rear 1/4 ties in.

Another very experienced body man that am working with, showed me a one piece '70 Chevelle trunk pan he had recently installed in a '71 W30 442 (he has also started metal work on my long time customer's '70 GTO). On the '71 442, he was reusing the furthest rear trunk structure out of the 442.He was also reusing the 71 trunk floors front shelf area as the '71-72 front "shelf area" is different than the '70 front pan/shelf area.

Am fortunate, my '71 & 72 Pontiac A-bodys have fairly nice bodys with rock solid original pans. Even my previous '71 Judge project which needed 1/4 panels & outer wheel houses had very solid floors & trunk & retains them today. Have broken down partscars before for these complete original panels & have several parts cars with perfect trunk floors & rear structure in them, so know a little about them, with one '72 partscar being disected very soon. It's just time consuming to drill all the spotwelds out & remove both quarter panels to get the back halve of a solid A-body down a clean rear structure/ full trunk pan with complete wheelhouses. Due to time concerns, what we ended up going with for the '70 GTO was a 3 piece trunk pan, as the GTO's inner wheel houses & the rear trunk floor (where it kicks up) as well as the reinforced structure behind it were not rusty at all. My suggestion was that we pick up a 3 piece trunk floor, as not only is the 3 piece much less costly, but much easier to install. Our longtime A-body bodyman concurred.. The weld lines will be over the trunk braces & carefully buttwelded, ground down, with very minimal filler, and will not be seen. Deciding to go that way, our next huge concern with the 3 piece was there enough kickup to the rear of the pan to splice it into the existing structure? The 3 piece kicks up about 5 inches so it no problem. This partiicular customer's '70 also neededa pair of full 1/4 panel's, outer wheelhouses, trunk drops, & floor pans halves. Front floor pans were a little soft, mid & reese floor pans were solid.. Ended up making a drive, saved close to $800 over rhe most reasonable catalogue vendors. Picked up all reproduction sheetmetal but the trunk drops, which had to be drop shipped from the Mfg & were here in a week. Though the trunk drops are made in the USA, they will need a little tweaking to fit, there is so much going on back there, that this did not surprise us. Hope this helps, without knowing how extensive the rust is in your trunk area, I can only relate our recent decision.

*Note: the front trunk shelf area, for a long time,has been a good place to examine and spot when non ethical "restorers" have used '71 & 72 "bodyshells" to "restore" '70 model A-body's (or vice versa) Unfortunately, have ran across such body swaps several times. Typically, not a happy ending, ESP when the car has been represented as something that it isn't.
 
#7 ·
Pinion head thanks for all that Info! You are obviously a wealth of knowledge. I totally understand your inbox being full. If I had that weather I wouldnt even look at my computer, so I appreciate it you taking the time. We have had 10 inches of snow today here in Chicago so ive had plenty of time to think about this.

I had purchased the 3 piece trunk pan originally with all the braces then saw the hacked up job someone had done previously to where the tail pan attatches and decided it would be easier to put in a 1 piece (so i thought). I am also replacing both inner wheel wells and trunk drop downs as those were pretty well shot. I have spent a fortune buying the 1 piece and the 3 piece pans which is my fault for not looking a little closer before purchasing. I noticed the front of the pan near the rear seat is different from the original but it didnt really bother me soo much as I am not going for a concourse restoration. Ideally what I would like to do is use the 1 piece trunk pan I have as it fits pretty well (and its paid for) and I think I can get the drop downs to work well with minimal fabrication.

My question for you is if I were to splice in the rear of the trunk pan at the bumper brace/rear body mounts back to where it slopes upward to meet the tail pan would it line up with the 68-69 pan? I think the indents may be different

Also do you know what model cars have the same trunk as the 70 Gto? Im assuming the lemans but what about a grand prix or even the Chevelle? I have contacted a few salvage yards hoping to find one but obviously they are getting harder to find and i may have to take out a second mortgage for shipping.

Sorry to be soo long winded. I appreciate the help!

John
 
#8 · (Edited)
Hi John,

So what did you end up doing for your 70 gto trunk pan? Im working on trying to save a 70 Judge that was a rustbucket and one of the first things I found out was the lack of a repop trunk pan on the market. I even called Ames and asked if they have any advance knowledge of any plans to make one and they say no.

So I am left with the same choice/problem as you, get the 68/69 pan and splice in the whole tail section, or go with the 70 Chevelle pan and deal with the ends of the tail section, and fabricate something to adapt bumper brackets. One other possibility is buy the 68 gto pan, and get a cutoff Lemans tail section from a salvage yard, but the guys who salvage these dont sell them for less than about $500 + shipping so it would cost me around 650 just for the old tail then plus the cost of a new 68 trunk. .

So, I bought a '70 Chevelle pan because I have almost nothing left of my original pan and nothing left to splice in. the Chevelle pan actually looks more like the 70 GTO pan on the inside at the tail, it has the 2 step-ups, while the 68/GTO pan does not.

I did my first test fit of the chevy pan today to assess how much metal fab it will take and here's my quick take.

1. will need to metal fab at the ends, to blend into the trunk drop-offs

2. will need to make some bumper bracket adapters. The Middle one will be easy as the Chevey has 2 female threaded holes behind the bumper, unfortunately they are vertical holes, while the GTO tail bolts go in horizontally, but still not a hard metal fab to make an adapter here. the 2 bumper brackest at the ends I have a choice, I can go buy a set of Chevelle brackets that will bolt up perfectly to the tail, but will require I drill 2 holes each side on the GTO bracket that attaches behind the gto Taillight lens. Or I can use my GTO brackets and drill 2 holes each side of tail panel and weld in Female nuts to accept the GTO bolts. I haven't yet decided which way Im going and which would look cleaner.

3. Looks like I may need to modify, cut/bend/weld at inside of tailpanel where trunk latch is welded in, just so it lines up properly with mating latch piece.

4. May need to weld in a somewhat flat piece of sheetmetal that will run the length left to right at the very rear where it welds into the upper tailpanel on car. Looks like the Chevy trunk is maybe an inch or 2 short to reach the very back of tail.

Here's some pictures for anyone else to see what you'll be dealing with if you go this route. And if anyone has ever done this before please chime in with any advice !! Thanks,

Chuck
 

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#10 ·
Hi John,

So what did you end up doing for your 70 gto trunk pan? Im working on trying to save a 70 Judge that was a rustbucket and one of the first things I found out was the lack of a repop trunk pan on the market. I even called Ames and asked if they have any advance knowledge of any plans to make one and they say no.

So I am left with the same choice/problem as you, get the 68/69 pan and splice in the whole tail section, or go with the 70 Chevelle pan and deal with the ends of the tail section, and fabricate something to adapt bumper brackets. One other possibility is buy the 68 gto pan, and get a cutoff Lemans tail section from a salvage yard, but the guys who salvage these dont sell them for less than about $500 + shipping so it would cost me around 650 just for the old tail then plus the cost of a new 68 trunk. .

So, I bought a '70 Chevelle pan because I have almost nothing left of my original pan and nothing left to splice in. the Chevelle pan actually looks more like the 70 GTO pan on the inside at the tail, it has the 2 step-ups, while the 68/GTO pan does not.

I did my first test fit of the chevy pan today to assess how much metal fab it will take and here's my quick take.

1. will need to metal fab at the ends, to blend into the trunk drop-offs

2. will need to make some bumper bracket adapters. The Middle one will be easy as the Chevey has 2 female threaded holes behind the bumper, unfortunately they are vertical holes, while the GTO tail bolts go in horizontally, but still not a hard metal fab to make an adapter here. the 2 bumper brackest at the ends I have a choice, I can go buy a set of Chevelle brackets that will bolt up perfectly to the tail, but will require I drill 2 holes each side on the GTO bracket that attaches behind the gto Taillight lens. Or I can use my GTO brackets and drill 2 holes each side of tail panel and weld in Female nuts to accept the GTO bolts. I haven't yet decided which way Im going and which would look cleaner.

3. Looks like I may need to modify, cut/bend/weld at inside of tailpanel where trunk latch is welded in, just so it lines up properly with mating latch piece.

4. May need to weld in a somewhat flat piece of sheetmetal that will run the length left to right at the very rear where it welds into the upper tailpanel on car. Looks like the Chevy trunk is maybe an inch or 2 short to reach the very back of tail.

Here's some pictures for anyone else to see what you'll be dealing with if you go this route. And if anyone has ever done this before please chime in with any advice !! Thanks,

Chuck
How did it turn out?
 
#12 ·
I am in the same boat as you guys with the 70's except I have a 71 GTO. My trunk floor will have to be replaced from the back seat all the way to the tail panel. I am also doing a 72 chevelle resto and I have a 1 piece trunk pan for that. My rear tail panel on the GTO that the bumper bolts too is pretty solid so I am thinking I should be able to graft that onto a 71-72 Chevelle 1 piece and make that work.. I hope!
I Believe the 71-72 chevelle 1 piece front section will be close enough but I will follow to see how you guys make out. I am a ways off from working on my car as I started the chevelle before I got my GTO.
I found a parts car that I was able to cut the tail panel off and between the original off my car, the chevelle 1 piece and the cutoff I pray I can make it work.
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