You just answered you own question without realizine it. 3/4 tons used a 14bolt rear end. 10.5" ring gear. 7000lb carrying capacity.
SBC Motors for the 20 series were the 250I6, 292I6, 307('73), 350 and 400. No 305's.
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Chris Lucas
1973 Chevy C-10
1975 Chevy Silverado
Captkaos' Page
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Chris Lucas
1973 Chevy C-10
1978 GMC Jimmy (2WD) - SOLD
1987 R10 twin turbo LS
1991 R3500 SRW CrewCab
1985 K5 diesel swapped project
1989 K5 2WD conversion w/ Vette susp Project
Captkaos Customs
73-87chevytrucks.com