so i have a 3/4 ton 79 chevy c20 its a 4 speed sm465
so my problem is that its very hard to shift and sometimes it won't even shift and when it won't shift i have to shake and wiggle the stick to get it to work again... also when i push on the gas in 3rd gear it slips out to neutral like theres too much power... so my questions is, is my tranny going out or is it missing fluid or what? I'm still a rook when it comes to tranny issues thanks in advance