question??

[dsm2ner]

wat does it mean when your tranny starts too shake alot when your driving also i drive a mustang lx 5spd if any one could help me out thanks. oh also we just put that tranny in today idk if we did sumthing wrong and it doesnt let me put it in gear i have too like turn off the car and then put it in gear?? did we aline sumthing wrong?? if any one could help me by telling me wat the problem is and wat i can do too fix it?? thanks