Many of the shaft couplers on QM series engines were set up with a tapered end shaft in the coupler.
How to verify:
Remove the coupler bolts and slide the coupler back away from the transmission, sufficiently in distance so that you can 'see' or feel with your finger if there is or isnt a LARGE nut on the end of the shafting. If there isnt a NUT on the 'nose' of the SHAFT, then this is a straight shaft connection ... and then follow the advice given in the other posts.
However, if you see/feel/find this large NUT, remove it, and then 'strain up' the coupler as with a 'straight shaft connection', .... remove any 'set screws, etc.' apply 'strain to the coupler as a straight shaft connection ....... and simply whack the side of the coupler with big lead hammer or with a steel hammer onto thickly folded 'cloth' held to the side of the coupler base (not the flange) ... usually the tapered coupler and tapered shafting will simply 'pop off' with a few 'whacks' - when the shaft to coupler connection is TAPERED (has a BIG nut on the shaft 'nose').