RE: 91AC drive washer
Yes they will fit. The reason for the change in parts was the woodruff key would beat the drive washer slot and the taper collet took care of that issue. Pull teh existing drive washer and woodruff key and rplace them with the FZ parts.
The part numbers you need are:
4325 - Drive Washer
4330 - Drive Washer Retainer (collet)