There are actually 2 if not 3 different cases. There is the 2wd case and a 4x4 case. The 4x4 case is called a "K" case as it has a letter "K" about 3" tall on the bell housing. The third I'm not positive of but I believe there is an hd case as well. If your guts are good, for $200 you can get a bolt on bellhousing from Jegs or Summit they use for drag cars. You actually cut off your bellhousing and bolt this to the pump comer bolts. It is super stout and saves the need for rebuilding a case.