Transaxle swap and now locked up

[81HoopT]

Ok, I'll go ahead and lay down the whole story. My dad gave his friend a 81 Rabbit diesel pickup for helping with his roof. It had a blown transaxle. We had driven for a couple years beforehand. (My dad blew the tranny) So this guy got a tranny froma junkyard and tried to swap it. He gave up and eventually skipped town. It's been sitting for 3 or 4 years. I'm starting school Tuesday and will be driving a lot, so my dad said that if I did the swap, I could drive until I finish school. (The Cummins gets 15 mpg as opposed to 45 mpg) So I remove the old one and find about a 3 inch hole in the diff case in the bell housing side. I threw in the new one with new hardware and clutch (old hardware MIA). I got it all together:fresh oil, filter, fuel, filter, gear oil, rubber fuel lines, and air filter. I figure its good to go. I bled the fuel lines, turn the key, and CLUNK! The starter is trying to turn the motor but it won't. The starter worked fine when it was off of the motor. Also, the clutch linkage is different. I can't hook up the cable to the lever. It should still start with the tranny in nuetral shouldn't it? It is an 81. Also, before I started, I checked that the motor and tranny turned.