well i found out the 4 speed in my camaro is a m21 and not a rock crusher like ide hoped whats the difference between the two and is the m21 not as good thanks for all the info you guys have been giving me i really appreciate it............. LONNIE:cool:

They have the same gear ratios, but the rock crusher is a super heavy duty unit. The rock crusher gets high marks for "cool" but in reality, is a loud, whinny tranny.

The gears on a M22 are cut at a 22.5 degree angle whereas the M21 is cut at 45 degrees. Hence the whine (and nickname Rockcrusher) for the M22.

The M-22 was developed for Corvette road racing; first known installation was a 1965 Corvette 396. The gears are stronger to withstand constant gear shifts under load. The rest of the trans is the same as an M-21.

Many ZL-1 and L-72 COPO Camaros were built with M-21 transmissions. No need to worry about it.

Try to think of it this way: You have a TH350, not a TH400 CX (top of the line rock crusher for automatics.) And TH350's work just fine.
Here's my rock crusher;
http://epitomesrebuild.com/images/177.JPG