I have a 2000 Chevy silverado 5.3 4x4 that kicks out of gear when you give it gas. Long story short I got on it one night and broke the rearend. I replaced the rearend now the only way I can drive it is to drop it in first when I take off and manualy shift through the gears. If I give it gas in 1st it kicks out of gear I can't take off on a hill or any kind of slant. I Have to lock it in 4 Lo to take off sometimes and it still slips if its in a bine. Any ideas on whats wrong with it?