being that your leaf hangers are bolted on, your truck has been modifed a bunch, the 8.00 15 tires work like this: 8.00 is side wall hiegth, and 15 is rim diameter, 8.00 + 8.00 + 15 = 31" stock original tires were 31" back then from factory, period.
G50 on a coil truck was 2000lbs each side
and G50 on a leaf truck was 1750lbs each side
G60 can only be had on coil trucks, so your frame was oriignally coil or your glovebox door was off a coil spring rea rtruck
G60: auxilliary rear springs; 500lbs each side, quote from 1967 GM data sheet: "not available when leaf type rear suspension is ordered".
good luck
© 1967 GM Corp
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A 68 C-10 panel and a 68 dually C-30 dump truck and a couple 71/72 chassis projects.
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