Manual Transmission Install Issues

[SBC RACING]

Hey Guys,

I'm in the process of swapping out my SM420 trans in my 62 shortbed (w/ small block) for a Muncie M21. I'm at the stage where i'm mating the transmission to the engine and the transmission only wants to go 3/4 of the way in and stop. I've done a couple trans swaps in the past and have had the same issue where the trans goes 1/2-3/4 of the way in and i have to struggle with it until it eventually goes in. This time around even after fighting with it for an hour or so it still won't budge..

Just thought i would see if you guys had any tips or tricks before i fight with it some more tommorrow.

Any help is appreciated.

Thanks so much