[reuelt]

I bought a second hand 3600BR from a pawn shop a few yrs agoand it seemed to have a differnt collet to that on my 3612C

View attachment 403557

Hitachi M12V has similar "one-piece" type collet. Newer models separate the collet and the collet nut.
Advantage of "one-piece" type collet is that we never hear of collet getting stuck in the motor shaft.