well u can grab the shift lever in back and make sure it goes in and out i think 3 postions but dont quote me on that

if u are looking at a tranny deff take some inner cv parts with spline parts to insert into tranny and spin like i said and make sure axle dont just pop out seen that many times

pull vss and look in it, look in diff for rust, and so on pull drain plug put ur pinky in the hole and get some fluid out if u can, gear oil=bad things most of the time