CH465 4 speed trans stuck in nuetral

[akram]

The truck is a 77 K10, I had the truck towed home after an ignition problem on a roll off and now the trans is stuck in neutral. I tried to take the top cover off thinking I could move the gears manually but the cover won't come off without driving out the pins that hold the shift forks. It acts like the trans is bound up similar to what happens when you have it in 4 wheel drive and you drive on dry ground and the trans get bound up and it's hard to get out of gear. I don't know what could have happened in such a short distance, any ideas?