jsw585

Just trying to fingure out what kind of tranny I have . It is a Muncie, but judging from listings by Colvin (Corvette by the Numbers) the puddle of numbers I have make mine a mutt.

Here are my numbers:

Maincase: 3851325 (64-65)
Sidecover: 3884685 (66)
Ext Housing: can't locate; is this on bellhousing?
Tailhousing: 3831731 (63)
Misc on maincase: P0829 (date?)

Does everyone agree my tranny was probably rebuilt/worked on at some point or multiple points, or is there other information indicating otherwise? I'm mainly interested in determining weather it's a Muncie 20, 21, 22. Is there any other way to tell if it's close or wide ratio besides the numbers and the sound it makes

Thanks for the help!!!!

JW
1963 convertible
Beginning modified restoration

legalgus

You're in the wrong forum. I'm an NCRS member and HIGHLY recommend you visit their website and become a member. The members know everything there is to know about older corvettes including restoration, numbers, etc.. The wealth of knowledge and their willingness to share is outstanding. They are all ready to help. I can guarantee you it will save you a lot of time and trouble. Sort of one stop shopping. Also, join your local chapter of NCRS.

JmpnJckFlsh

This thread probably should be moved to Factory Resto.

I can tell you that you may have a mongrel trans assembled from parts. The main case stamp "P0829" identifies the main case as originally being installed in a 70 Corvette (VIN number should be nearby), and was built August 29 (70?). There should be a suffix after the P0829...A is M20, B is M21, C is M22.

It should be pointed out, however, if the trans is assembled from parts, there is no way of knowing what is inside. Another way of determining if the trans is M20, M21, or M22 is to count the circumferential grooves on the input shaft: I BELIEVE (wouldn't bet my life on this) if the input shaft has one groove, it's a wide ratio; if two grooves, it's a close ratio; if no grooves, it's an M22.

Edit: Two circumferential grooves on the input shaft is a WIDE RATIO...one groove is a CLOSE RATIO, and no grooves is an M22.

jsw585

Yeah, I thought it might be a mutt....I didn't see a prefix before the date stamp, but I'll look again. Looking over the Colvin book a little closer affirms what you said, too.

What part of West Texas are you from? I am originally from Las Cruces, now living in San Antonio.

Thanks for the input and for moving this thread to the right location!

JW

JmpnJckFlsh

Not a prefix!...A suffix. The suffix letter will be located AFTER the build stamp, e.g. P0829A (wide ratio).

Las Cruces is close...I'm in FAR west Texas; as far west in Texas as you can get. I'm NCRS member 20817...Our national convention will be in SA August 1-5, and we're looking forward to it. You should join up if you're planning a restoration on your 63; it'll be a big help to you and costs next to nothing.

JohnZ

Nope - all the P0829 says is that it was assembled on August 29th; there was no model year designator until 1967, and there was no ratio-identifying suffix code until after mid-October, 1968.

jsw585

So if I read you right, this could be a tranny from 1970, in which case I might expect to find a *suffix* (thanks for the correction earlier), or it could be a tranny from pre 68, in which case it would not have a suffix and could still be a M20, 21, or 22 for that matter, which would lead me to ID it from here based only on morphology. Does that sound right? Thx!

JohnZ

Nope, it's a '64-'65 main case with a '63 tailhousing and a '66 side cover. Put it in first gear and count how many input shaft turns it takes to get EXACTLY one turn of the output shaft; 2-1/4 is a close-ratio, 2-1/2 is a wide-ratio.

jsw585

sounds good. thanks so much for the help. hopefully will find some time this week or so to investigate.

5speeds

Here is a link for Identifying Muncies that I wrote. It's been copied by many people....

CLICK HERE