I have a 75 3/4 Chev 4x4 with the automatic hubs and want to switch to manual hubs. My questions is witch hub do I have I comapred mine to my dads 3/4 chev and is much smaller in diameter? Where the manual hub bolts up is approx. 4" dia and has 6 bolts. Which hubs do need to order and do I need to do anything in the transfer case???