ox66 lower unit not going back on

[choptanksparky]

Hi everyone, I'm new to the board.
I picked up an extremely low hour 200 hp ox66. It has only 26 hours based on the Yamaha multi gauge on it and has been sitting a long time. Condition is pristine.
I pulled the lower unit and replaced the impeller. Now trying to reinstall the LU, it goes nearly all the way on but not fully. It stops about 3/4 to 1"shy of fully seating. I've rotated shaft and that doesnt help, as a matter of fact it makes it worse. The water tube and shift shaft "appear" to be lining up when I peeked in there with a flashlight. While the LU was off, I did move the binnacle shifter position but returned it to neutral before reinstalling the LU.
Any ideas?
Does the shift shaft coupling have an "index" mark?
Thanks

 

[99yam40]

find some help so you can watch everything line up while sliding the lower unit up to make sure all lines up properly.
I hope you cleaned and greased the splines on drive shaft and you did not get a big glob of grease on the end of the shaft.

tilting the motor helps,so you are not lifting straight up and holding all of that weight.
if lower unit and shifter are both in the same gear (forward or reverse) you can turn the prop shaft to turn the drive shaft to align the splines to the crankshaft hole

 

[scoflaw]

From all the attempts your lower unit might be in gear. Confirm neutral at binnacle and lower.

 

[choptanksparky]

Well, finally found time to spend on the engine. Scoflaw you were basically correct. Even though I could see everything line up, what I couldn't see was that the splines inside the shift coupling were not. Adjusted male spline to neutral (as was binacle) and she slid straight on.
Small tip I saw on a video.... When doing this alone, use a ratchet strap to assist. Remove the cowling, one hook of strap on one side of engine, take strap under the cavitation plate then up and hook on to the other side of engine. Use the ratchet to raise and lower the LU.

Thank you very much for your responses