[poncho-mike]

I'm trying to help a friend out with a 1969 GTO find a 1969 M21. I thought I had one, but when I dug it out I found it marked 1968 M21.

Many years ago I parted a 68 HO GTO and a 1968 Ram 1 GTO, so I'm thinking it is off one of those cars. Will this be the same case and p/n's as a 1969? The code P8E31 is stamped into one side. I took a few photos that show the case stamping and p/ns.

I'm not that familiar with pre-1971 Muncies, so can some of you experts weigh in?

Thanks,

Mike

[poncho-mike]

More pictures

[poncho-mike]

Last pictures.

[Cammer-6]

I have a 68 M-21 that was NOS for sale so you can match up to yours.
Im pretty sure I have a 69 M-21 main case in my parts
and probably most parts(sams input) to assemble.
Both cases will be 660

[Mr. G]

The number 3925660 on the main case was the same number used for '68-'70 cases so it would be the same as the '69 M-21.

[poncho-mike]

Were there any date codes?

How does the P8E31 break down? Was that on 1969 Muncies?

Mike

[johnta1]

P8E31 - May 31, 1968

Should have a partial VIN on it where the tailhousing mates to the main case on top.

[poncho-mike]

That's too late to be the 68 Ram I car. That car was odd because one of the 31's was manufactured with a "670" style casting, while the other was dated three days later and was based on a 1968 style casting. I want to say those were November 1967 cast dates.

I found partial VIN, but it's not entirely legible. It starts with an 8 or 9, then there is a M, and the last five digits are 12312 or 12812. It was stamped light on the left side bottom.

Does the P in P8E31 stand for Pontiac?

Mike

[gto4evr]

the trannies will be identical functionally except for the shift rod attachments. the 68 used a smaller shift dog that had a stud on with a nut where the 69 the square cutout for the shift arms was increased in size and used a bolt through.

There's a few options here. first off, if he's using the original 69 back lock shift linkage that connects to the steering column then just change out the shift dogs on the cover because there's no conversion option to hang the back lock linkage off the 3/4 mount on a 68 shift dog. If he's not running the back lock linkage, you can you can just run the 68 shift arm plates. Or you can use the adapter inserts and fit over the studs to use the 69 shift arm plates and just put a nut on it.

I've just gone through this myself because I insisted on getting the car set up factory correct to use the 69 only backlock on my 69. the repop stuff is modeled off the 70-72 setup that uses a different stud on the 3/4 mount along with a different pivot. (ames and the other companies out there selling the back lock linkage all say "69-72" in their description, but it's really only 70-72 so you can't mix parts if you have a 69 pivot. the pivot stud must match the year of the pivot bracket. No one makes the 69 pivot stud. I ended up making them myself when I found the issue with the reproduction ones. I made up a few of them, saved the two I needed for my two projects and sold the rest on ebay a few years ago.

again, all this can be eliminated completely if you don't care about the back lock stuff. Hurst makes an aftermarket switch and bracket that bolt to the back side of the shifter body to engage back up lights when in reverse instead of the factory setup that rotates the column for the lights (along with the fact that you must be in Reverse to turn the key to the off position and remove from the column)

I'm still trying to get used to that fact since I've gotten everything correct. 30 years of driving this car parking it in whatever gear I felt like is a steep learning curve to try retraining myself to always park in reverse before the key will come out!

[johnta1]

Does the P in P8E31 stand for Pontiac?

No, it's means a Muncie transmission. Saginaw and others had a different letter.

[Cammer-6]

Also a 69 will most likely have the gear ratio code stamped into it
A M20
B M21
C M22

[Cammer-6]

I bumped the one I have for sale as to clarify the date code

[poncho-mike]

The friend who needs a tranny has a 1969 Ram IV GTO that was built in March or April 1969. It currently has a 73 Muncie with big input/output. The tranny I have is dated about nine months too early. He's starting a full frame-off restoration on the car. What is his best option? I think he mentioned he saw a case with no numbers for sale.

[Cammer-6]

If I can hit the storage loft at a cool time I can check the date on the code "B"
69 case I have,if interested.

[RMMAN]

I am the friend of Poncho Mike who was discussing a 69 Muncie with you. On 9/04 you posted you may have a 69 M21 case #3925660 with the correct "B" code for a M21. Do you have one to sell and what is the date code on it?

[Cammer-6]

PM sent

[Cammer-6]

Looks like we are SOL on the 69 M-21 case
Casting # and date stamp shows 1970
Still has a cluster gear in the case,and I have a main gear set already put together with new parts but alas
its a 1970. :^(

[RMMAN]

Thanks for checking to see what you had. I guess its like trying to find a needle in an old haystack. If you know of someone else who has some old haystacks I should try, please let me know.

[Cammer-6]

I do have the M-21 that was over the counter(no VIN stamping) with a 68 part # tag
which would be OK as a service replacement.