Trans assembly date vs vin number
 

I am working on this Corvette that has a Muncie trans and 12 bolt rear end. The muncie build date is 9PA but the vin is a 672 vin that seems really far apart and there is no way it is a restamp. The car also has a BV rear end.

67XXXX cars have all kinds of weird dates.
I am assuming you are talking about 69 Camaro stats, since the trans and rear you posted appear to be from a 69 Camaro.

67XXXX would be an 08A or 08B car, guessing 08A. My 08A Z is 671122. Being the first week of the "70 model year" cars (remember 69 Camaro and Corvette production went on into Nov. and Dec. respectively, but anything built after Aug 1 had to comply with 70 model yearFederal standards) the 69 Camaros built in the first two weeks of Aug got a lot of crazy numbers. GM was using up ALL the engines, rears, etc. they could scrounge together, as July was NORMALLY down month for engines and trans. Not uncommon to see an April or May component in an 08A car. The April rear makes perfect senst for an 08A car. Not unusual at all in my opinion, but I would defer to Kurt and the others at CRG.

Now, is it possible that a left over January part (trans) was used? Absolutely. Likely? Who knows. I believe there is documentation of an October 68 built engine in a September of 69 Z. So, it is within the realm of possibilty. Have seen several 08A cars with April, May and June Transmissions. Not at all out of the ordinary. Would assume the same would apply to rears.