If you are asking about 6.1068 below, the answer from the 1939-53 GMC Master Parts Book is that there are 3 different parts used depending on models 350 and smaller. I'd guess that larger than 350 series would have their own.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
