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Discussion Starter #1
Hello all,
Here's my conundrum with my number correct car; Engine and all components..correct, M20 WR Muncie with car VIN stamped numbers/letter and the julian date stamped in. Except w/o removing and disassembling I have not found any way to say its a true WR. Perhaps someone who has thousands and thousands of miles/hours driving might know that answer by driving the car. The Pontiac info says tho a WR would not be used in any car with a gear ratio of 3.73/3.90 etc., only in cars with 3.53 and down in numbering, mine is a proven 3.23 rear gearing standard rear end.
Now for ID'ing the 3rd member, Pontiac stamped a code letter and the gear ratio on the r/r axle tube, painted a color code on the top of the housing and painted the out board axle flanges with that same color. After 48 years of survival the paint is gone. The dilema is this; on the ring and pinion are the stamped number of teeth to proove its a 3.23..13/42. But on the axle tube the letter code which is suppose to be K then 323 has a P 323, all the reference material states P=3.90 and K=3.23. So does this affect, as in nulling and voiding it being a verified correct numbered car or do we go with it is, but an employee must have stamped it wrong 48 years ago? This may affect the value so it is important to resolve, which may never be doable. :confused Tom
 

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I assume the car is a '64...From '63 thru '65, a wide ratio M 20 had no grooves cut into the input shaft. They also had lower gearing than the '66-up wide ratio units...from '66 up, the wide ratio had TWO grooves cut into the imput shaft. The close ratio M-21 had one groove in the imput shaft. The casting # for '65-'67 M-20's is 3885010. As for the rear end ID, very easy to mis-read the letter code, if it is at all legible. I wouldn't lose too much sleep over it myself. Do you have PHS on the car??
 

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Discussion Starter #3
You assume correctly. Yes I have the PHS Documentation. I had the trans out, if the input shaft is the shaft that goes into the clutch/flywheel/crankshaft I cannot with any certainty say I noticed any grooves, tho I think I would remember as I spent some time cleaning and checking numbers on the trans.
As for the axle tube the letter "P" is unmistakable and preceeds the 3.23. I have another reference book that shows the pic with the letter following the 3.23 but after much cleaning that is not the case, there are no other stampings. I'm well past losing sleep, it's a $ thing now which I am concerned about as I have paid for an inspection to absolutley document the car as number correct. I'll have to now wait for those doing that work to make a decision and live with their findings. Thanks Tom
 

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In 64 and 65 pontiac used olds rear end housings, I would be inclined to think the P is an indicator that the rear end is for use in a pontiac and not the 3:90 metallic brake rear end. I'm reading alot of conflicting information regarding the 64 rear end codes, some say the stamped code should be the R&P gears (42:13) and some indicate it should be the actual ratio. Some list the tube coding as 3.23 L for metalic brakes with the letter code following the ratio and some don't list the letter code at all.

The picture below list the casting number and date code for a August 64 rear end, have you compared the date code to your car's build date?

 

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The info I have shows P being a 3.90 too. It also shows both K and L as being a 3.23. With all the conflicting info out there it may be tough to prove the originality, BUT, it will also be tough to disprove it too............ x3 on losing sleep........
 

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Discussion Starter #6
Number Correct Car

68,
Thanks for the info. My book; Cars + Parts magazine...Pontiac GTO ID Numbers 1964-74 states about axle codes; "Pontiac used 3 forms of ID on the 64, first is a letter stamped on the back passenger side of the axle tube, the second is a sticker containing a two letter code, and the 3rd is a color code painted on the top of the differantial and the ends of the axles.
Which end of the axles? Without removing either the brake drum or the axle to see the splined end where is the paint? It goes on to give the colors for all the different ratios, the 3.23 can be brown, brn and green, or just green. You are right, the stamped alpha letter is either K of L. How did a P get there, good question, also agree with you about disproving or proving. Thanks. Tom L
 

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Discussion Starter #7
Number Correct Car

05,
Thanks for the response. I cannot find anything stating the usage of Olds parts. I did find a statement that says the 69 Pontiac could have a Buick trans housing and gears with an Olds rear end.

We cleaned and scraped crud but could not find the casting ID as you show in your picture. Where is it?

Thanks. Tom
 

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68,
Thanks for the info. My book; Cars + Parts magazine...Pontiac GTO ID Numbers 1964-74 states about axle codes; "Pontiac used 3 forms of ID on the 64, first is a letter stamped on the back passenger side of the axle tube, the second is a sticker containing a two letter code, and the 3rd is a color code painted on the top of the differantial and the ends of the axles.
Which end of the axles? Without removing either the brake drum or the axle to see the splined end where is the paint? It goes on to give the colors for all the different ratios, the 3.23 can be brown, brn and green, or just green. You are right, the stamped alpha letter is either K of L. How did a P get there, good question, also agree with you about disproving or proving. Thanks. Tom L
Tom,
That's the same book I'm using. After all these years, I don't think you're going to find paint marks anywhere....
 
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