Ed and Dawn sell the Chef's Specialties mechanism at exotic blanks. CSUSA sells a similar mechanism in their "deluxe" pepper mill.
The crush/grind mechanisms come in both a shaftless variety and one with a shaft. I've not tried the one with a shaft, but I didn't like the shaftless. I think Chuck uses the mechanism with the shaft -- they look more reliable to me (I've got to try one).
The shafts for both the crush/grind and the traditional grinder can both be cut to length, so you don't have to match up exactly with the length of the shaft.
-Barry