'67 Muncie numbers

[Jeremy Hedges]

First of all, the judging manual does say anything about the numbers on the muncie, correct me if I am wrong. If you have a judged, are the numbers on the muncie judged? The date? I have a '67 435hp 4:11 rear end thatI am restoring with the wrong muncie. It is supposed to be a close ratio M-21. What would be the correct casting numbers for the muncie? Main case, tail shaft, side cover, front bearing retainer? The car is VIN#9608. Built date of Feb, 1, 1967.

Any help, Thanks

Jeremy Hedges
#31711

[William V.]

Add to the question on '67 Muncie numbers

I have a similiar question as Jeremy's. Except I want to add that in my muncie parts list the 65-67 main case (3885010; bearing support all years (3831752; and 65-70) mainshaft extension assy (tail housing 3857583)are the same for the m20 m21 & m22. Thus I figure that there must be a stamping to undicate what gears were installed. Am I correct and if so where can the information on the stampings be found?

66-70 Side cover part(3884685)
64-67 Main drive bearing retainer (3851326)

Thanks

[Wayne M.]

Re: '67 Muncie numbers

Jeremy -- although I don't have a '67, my take on the judging issue, as you say, is that numbers on the transmission don't count. In your case (no pun), this could mean you could have a late '63 "704", a ''64/65 "325", or the correct "010" maincase. Later cases "660" and "661" would be a configuration giveaway with the wider stamp pad flange, and for the "661" the drain plug.

I believe the NCRS non-judging of transmission casting, assembly or VIN derivatives is due to the difficulty of visible access, short of jacking the car. This does not prevent the judges from evaluating the bellhousing cast #, though.

For your car, it would be the "010" case, the "584" tailhousing, and the "685" sidecover. Other than having the correct VIN derivative, the assembly date should preferably be 1 to 3 weeks before final production,ie. (say) P7A07 to P7A25, depending on the combination of close-ratio and rear-end ratio (ie. 3.08 to 3.55 rear ratios with close ratio transmissions would have the wider spread).

For flight judging, they can't "see" close or wide ratio.

Consider yourself lucky. If you have the wrong engine "case" cast #, or have a case casting date later than vehicle assy, or prior to the 6-month window, you lose BIG time.

[Wayne M.]

Re: Add to the question

Bill -- an excellent source of information for Muncie #s is Alan Colvin's Chevy by the #'s, '65-'69 version. The '65 maincase is 3851325 until the end of '65. Tailhousing is cast # "584" (one digit more than the part #). When mounted to the motor, you can't see any exposed #'s on the bearing support or the front bearing retainer. Ditto the identifier for M20/21/22, which was the # of rings (0,1,2 in '66-67, and 0,1,0 in '65)on the input gear splines. Muncie didn't begin the close/wide/rock crusher codes on the trannys until Oct 21, 1968 (A, B, C, respectively).

[Jim B.]

Re: Add to the question

Wayne

I am an original owner of a 1968 vett and it has an M22 with the requisite "C" code on the transmission along with the last part of my VIN. Build date was in July of 1968. So they must have been doing it then.