Pops out of 3rd gear? Sounds like it's time for an LS-swap!
Sorry. I'm beginning to think I've been programmed
Yeah yeah, just kidding. Glad you found another transmission that will go right in. You don't need granny gear anyway.
Getting into newer years, my buddy has a '55 1st Design, original 6cyl/3spd. I gave him a 3spd out of a '72 that bolted right in on that first year open driveshaft. Now he has full-syncro 1st