Old school KAC Aimpoint mounts.

Three questions.

The old school KAC Aimpoint low profile mounts that resemble the KAC 1 piece scope mounts -

A - Are they absolute co-whitness with Irons?
B - Are they durable?
C - Do they fit both the Aimpoint M2, and M3?

I have an Aimpoint M3, and I just traded a few (2) Colt M4 stocks for an old KAC mount. (He got the ass end, but he’s convinced it’s great. Irons only KISS lover. Guess we both got what we wanted.)

Might throw it on the car gun. Worth it?