Are you pulling the engine and the transmission as a unit?

Gotta be something still attached. The two side mounts for the engine, the exhaust, the center mount for the transmission, the transmission linkage? Don't pull too hard until you locate the problem there's things that can bu stuck and release a lot of energy when the break free causing damage or injury.

Remember too that when pulling an engine you need to pull forward and up.

Pictures may help..

Good luck here.

Glenn