Yes. Easiest is to jack up one rear wheel while leaving the other on the ground. Mark the jacked up wheel and the transmission end of the driveshaft so you can count rotations from under the truck. Have your helper slowly turn the jacked up wheel exactly one turn while you count revolutions of the driveshaft. Divide the number of driveshaft revolutions by 2. The result will be your ratio. Most likely a little over 4 because the original rear end on '51 half ton trucks had a 4.11:1 ratio.
'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.
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