As joe said, if it’s a runable motor that’s not a bad idea to run it with the lower unit loose and it will drop off. Correct me if I’m wrong but I believe the Chrysler outboard motor books said to do just that. You’d want to disconnect the shift linkage too.
What I use is a slide hammer that has been welded to the adjusting screw of vice grips. Just make sure you grab ABOVE where the seals are and hammer away. Resist the thought to pull directly vertical from the splines, you will ruin a perfectly good driveshaft that way. Using the slide hammer on an angle has never failed me and I’ve had some STUCK ones. You can tap the drive shaft back in a little once it starts moving to help loosen things up.
There are actual slide hammer kits that come with a vice grip attachment but welding one permanently was much cheaper since I already had everything.
