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Been thinking if I should rebuild or just buy reman rear axle and transmission for my 69 gto. The cost of rebuilding might not be worth it, what Benifits would I get if I bought reman trans and axle. The prices vary from 1k to several thousands. My gto is intended to be a possible daily driver with rare occasion hitting the gas peddle little.

Info: 69 gto factory A/C 400 block
Automatic transmission hydromatic
 

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I don’t know what the issues are with your drive line on the goat, but if you have deep pockets I would look at overdrive on the transmission. That way you can run a 3:55 or higher with comfortable rpms
 

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"If it ain't broke don't fix it."
If you must spend money I would be much more comfortable having my hardware rebuilt than going with someone else's problems. Figure that there is a reason the rearend or trans was available to the rebuilder and the parts used in the rebuild could be much worse than your current parts.
 

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nothing wrong with neither, wondering if just buying a ready to bolt has more benefits.
Nope. Automatic cars are much easier on the driveline in general. The TH-400 is a specific build to the GTO if yours is still orginal. The trans had higher line pressure and the ability to shift manually - other mom/pop Pontiacs with TH-400 are not the same. If you simply wanted to purchase a rebuilt just because and wanted to set your original aside because you plan on doing figure-8 burnouts to show off at the Friday night Burger King get-together, then I can see it.

The TH-400 is pretty rugged for a street car, but if you are looking to put more HP into the engine and do a lot of weekend racing, then upgrade. If your TH-400 is operating fine, leave it alone. If you do have it rebuilt, make sure your trans is rebuilt and not swapped out with some other rebuilt off-the-shelf TH-400. You will have serial numbers on it - write them down and take a few pics. Sorry to have to suggest this, but it seems there are many shady people.

Same with the rear end. Behind an automatic, they are fine. If you have a posi and add wide sticky tires and plan on doing those figure-8 burnouts and revving the engine up to 6K in neutral and dropping the stick into D in an attempt to lift the front tires and impress the Honda guys - then get a better rear end. If you have any leaks at the pinion, you can have a pinion seal installed. It wouldn't hurt to have new axle bearings/seals installed as they are more apt to go than the carrier bearings.

If you need peace of mind, add a towing/road service package to your car insurance or get AAA.
 

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Cameo Ivory 1967
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450 hp is a lot to ask from bolt on parts... unless extensive head work is mixed in. In any event, a TH400 and BOP axle will handle that, so long as you're driving it, and not beating it.

Put up some pictures when you can, so that we can judge the condition and originality of what you already have. That'll help to guide you
 

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... Won’t be doing any crazy racing or figure 8s.
Yeah Right! :ROFLMAO: 450 HP, a TH400, and the right set of gears would be way too tempting for even a grandma! (y)

My opinion on which way to go with the rebuild or buy already rebuilt.

So long as your pieces are working as they should, or close, AND you want to spend the money now...have them rebuilt. Many of the rebuilt-off-the-shelf rear ends or transmissions ended up in the rebuild shop because they blew up at some point or where found in a fence row sitting for who knows how long. You won't know if they are good to go until you have them installed AND it's much easier for a shop to rebuild one that was working than otherwise. Like others have said MAKE sure you get yours back and not a fence row bum with fresh paint. Never turn in a good working piece as a core.

As far as the horsepower goals, not that you asked, I would stick closer to the 400 HP mark for a fun driver with a rear gear set around 3 to 3.3:1. Given your previous comments mean that you are a mild driver. My old set-up on my 67 had about 400 HP with, ready for it, 2.56 single-wheel-peel rear gears (and the TH400). It was a blast to drive, not too much power, decent mpg's at 55mph (17 mpg), and highway geared to keep it from tearing itself up. It still ran in the 14's in the quarter. You had to try to drive it up to self-destruct mode and still could not get there. It was still risky to drive in the rain due to spinning the tire/s...you had to be real easy with the go peddle to keep it stable on wet roads.
 

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What Pontiac Jim said, in spades. If it were mine, I'd leave the original parts alone unless they needed service, then I would service them. Original parts are almost always superior to 'reman' or exchanged parts.
 
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