Does heavy duty suspension=M-22?

Hi, my '71 LT-1 is at the mechanics now to perform some odds and ends including replacing the rear leaf spring. I have not determined which transmission is in the car, but my mechanic says that it is definately the heavy duty spring (which is original, we believe). Any chance I have an M-22 in the car? It is not a ZR-1 package. When the car goes up on the lift, it will be determined definitely, I am just curious if there is a chance that it has the rock crusher.......

Dave S.

[JohnZ]

Not likely - M22 was only available in 1971 with the LS-6 454, and only 130 M22's were built.