Originally Posted by sapsz28
My 1980 Z28 has in it a M21 matching # muncie which I had rebulilt this summer and exept for seals the tranny was inn perfect shape with 116,000kms on it or 100,000miles,people dont beleive me untill I show them them the build sheet and they take a peak under the car, beautifull tranny had her sealed with castrol syntec 70w90 gear oil which will outlast the tranny but still every 2 sesons regardless of mielage I change the fluid, preventative maintenance goes along way.
Are you saying you think your 1980 Camaro came with- as in originally equipped with- a Muncie M21?
In "GM speak" RPO code M21
or whatever do not refer to the tranny maker, just a 4-speed close ratio.