I am having trouble with getting my out drive back on I can get all the way except for half an inch into place I have it in forward gear and have tried several times it seems like something is stopping it. the threads dont come out far enough to start the nuts, and I tried using a light hammer to tap it but afraid to hit it to hard. How do I fix the problem and get it to atleast thread on the nuts

What drive ???

I'll assume Bravo drive.

Sometimes they will slide right in sometimes you need to use the nuts.
If it went in nicely till 1/2 from bottomed then the splines are engaged already.Mine sticks here also but I just use the nuts to pull it in evenly.It goes in easily with them.Some will say the alignment is a bit off.I'm not so sure about that.

Make sure your splines have all the "old" grease out and fresh grease on them.

You should be putting the drive on in neutral to make sure the cable gets in the clasp.Bravos are not to be shifted when not running.

Not an expert but I think the O-rings on the shaft are causing your hold up. Maybe a few light taps with a rubber mallet?

The O-rings can do it also...especially if they are new.

Align Tool needed for Engine