Muncie M21 dated P9B17

[rlw68]

Originally Posted by enio45

is that , i assume a late car? Would it have an A, B or C after it, if it was late production?

The car was built in February. Should the stamp on the trans include the B code for M21? It has the original engine and rear axle (4.10!)

thanks,
Rob

[Steve Shauger]

Rob, the letter suffix stamped after the assembly date on transmission denoting A=M20 ,B=M21,C=M22 is not designated on Protecto plates. Your Z28 could have come with any version trans, but the most probable is M21, so percentage wise Bor M21. I've owned/own Z's with all three configurations. Early 69 built cars with muncie trans didn't have the suffix stamped but based on your build date it would have.

[Steve Shauger]

Just to clarify, Muncie transmissions built after approximately Oct 20th of 68 were stamped with the suffix trans designation A, B & C

[rlw68]

Originally Posted by Steve Shauger

Rob, the letter suffix stamped after the assembly date on transmission denoting A=M20 ,B=M21,C=M22 is not designated on Protecto plates. Your Z28 could have come with any version trans, but the most probable is M21, so percentage wise Bor M21. I've owned/own Z's with all three configurations. Early 69 built cars with muncie trans didn't have the suffix stamped but based on your build date it would have.

The options on the sales doc has '4-speed trans' separate from 'Z28 Equipment'. Thats interesting since the 'rear axle ratio' listed by itself is for the 4.10 gear. Would it be common to use the M20 or M22 with this setup?

[Steve Shauger]

Originally Posted by rlw68

The options on the sales doc has '4-speed trans' separate from 'Z28 Equipment'. Thats interesting since the 'rear axle ratio' listed by itself is for the 4.10 gear. Would it be common to use the M20 or M22 with this setup?

They only built 1200 or so Camaros with M22 solid lifter only, built 44,000 with M20. and 13,000 with M21. The majority of Z I've owned have been equipped with M21's. For drivability, due to low torque 302, the M20 is the best performing.