Can somebody help with recommendations for installing an LA onto a 833?

We sent 3 hours yesterday and could only get it about 1/2 from being seated fully. We were putting so much force without it going in, that we were worried something was wrong - it was also then dark outside. Pulled it back out and everything seems fine - no gnarled teeth on either side. This engine and tranny has even been together before.

Is it really just that difficult? Is it easier to just pull the tranny and install them together?