well it certainly looks like thats your problem jb,wrong tulip in the diff...that must mean its a non lsd box,but who knows! its all up in the air now,nothing seems to make sense re the bar in the diff etc...ive got a box here that looks like yours in the diff,wheels rotate same direction when the box was on the car,but off the car and off engine they rotate opposite...although its def a rev3 lsd box...its mad!
Your tulip is too long for that diff basically,the correct tulip will sort it.
If anyone has any ideas on how to guarantee identification of these diffs id love to know.The best way to make sure its going to work is to get the shafts and gearbox from the same car.