Tool
 

I have an alignment tool, which i used to adjust the engine height. That will go in and out of the coupler easily. The shaft on my outdrive along with the extra outdrive shaft that I borrowed will not go into the coupler at all.

Fixx
 

did you replace the o'rings on he input shaft??

Greece them and once you slide the shaft in as far as it will let you, give it a swift kick,,its probably hanging up on the o'rings that go through the gimbal bearing..

O rings
 

I actually took the orings off the shaft once I began having trouble. The shaft will not even go in with them off. It is definatley a metal on metal collision between the shaft and coupler.

I one time had a home made (not by me) alignment tool that was not the right diameter. Validate you have the right tool, it sounds like you do not. Also make sure you are getting the spherical part of the gimbal bearing aligned properly or the drive will never go on.

The Solution Is Found!
 

A buddy of mine felt around in the coupler and thought he noticed a couple of the splines on the end has some burrs and felt a bit roughed up. He put a small file on a dowel rod and in about 15 minutes the drive was able to slide into place! Thanks to all the suggestions from everyone they are greatly appreciated. Phhewww --Boating season is on again!

Fixx
 

are you sure you have the rite bearing??

i have seen those ebay aleignment tool to be off by .010..my merc one is has alot tighter fit..

make sure the center of the bearing is center with the coupler, the center of the bearing will rotate,stick the alignment tool back in and take a dead blow hammer and smack the tool @12-6-3-4 o'clock to center it..if your tool is a loose fit that may be the problem..

also make sure the coupler is not packed with Greece,it will hydraulic and wont let the shaft slide in easy,,make sure there's no rust or even a burr on the shaft also,,its a real tight fit and that will stop it from going in..slao look for a twist in the coupler splines and shaft..