Need help with Muncie ID

[Brian Monticello]

My muncie has a casting of 3925660 which I believe tells me its from 68-70. I think the other number tells me its an M22 from June 28th 1968 with a marking of what I THINK is P8H28C with the C designating the M22 ratio. This trans is currently installed in a 65 327/300 car.

Can someone verify my hunch - the link below shows the numbers


Thanks!
Brian

[Joe L.]

Re: Need help with Muncie ID

Brian------

The '660' main case was used for 68-69. It may also have been used for very early 70, but I don't think any 1970 Corvettes would have had one since they were a late model introduction (January, 1970). Your particular transmission was originally installed in a car of the 1968 model year and was built in June of that model year. In this case, that should be June 28, 1968 as you have surmised.

The "C" suffix codes does designate an M-22. However, the thing that I don't understand about this is that the suffix coding system was supposedly first used in late October, 1968. So, it would seem that yours is a bit too early for this. But, who knows? Does the "C" look like the same font style as the rest of the characters in the build code? For the 1968 model year, the '660' main case would only have originally had the drain plug if the used for an M-22 application, but the plug could easily be added later by someone.

In any event, the "C" suffix code would only identify what gears were ORIGINALLY inside the case. MANY Muncies have been "mixed-and-matched" over the years. Cases are often replaced with another used case from another transmission when some klutz decides that he's going to "pull in" the transmission to the bellhousing using the transmission mounting bolts. This usually results in a broken off mounting "ear".

[Brian Monticello]

Re: Need help with Muncie ID

Joe,
Not sure if the "C" is the same font but it IS lower case while the rest are upper case. It doesn't make any noises that sound like rocks being crushed! My drivetrain is like frankenstein... a little bit from here and a little bit from there so I'm interested only out of curiosity.

AS always, your expertise is greatly appreciated.
Brian

[Joe L.]

Re: Need help with Muncie ID

Brian-----

What about the drain plug on the forward, lower right side of the case. Does it have that feature?

[Craig S.]

Re: Need help with Muncie ID

Brian - if it really is an M22, it should have a fair amount of whine do to the less sharp gear pitch....Craig

[Brian Monticello]

Re: Need help with Muncie ID

Joe,
It looks like there was a drain plug at one time. Check it out.

I bet if I investigated the history of my car a title search would turn up BUBBA somewhere along the way. Oh well... I love it anyway.

Looks like I have a M22 case w/o M22 gears.

Thanks

[Wayne M.]

Re: Need help with Muncie ID

Brian -- all non-M22 cases have that circular pattern in the cast of the (future) drain boss. Also, the "C" should be the same case and font as the other Muncie date #'s. According to Alvin Colvin, the suffix designating gearset was not applied before Oct 21, 1968.

[Joe L.]

Re: Need help with Muncie ID

Wayne and Brian------

Yes, the configuration of the casting boss is exactly the same as it is on all non-drain plug Muncie cases. So, this and the other "irregularities" pretty much confirms that some "clever" joker added the "C" to the production code.