Interesting side note...
Went through the specs for the 1965 C1504 and the C2504, the 8ft stepside C10 and C20 respectively (both my C10 frames are 8 ft). If they have the same wheels/tires and the lugs are covered, they are visibly the same truck. The C20 has mechanical advantages in the chassis, brakes, rear end and suspension. For that year, the C20 has the advantage of 8 lugs...8 lug wheels are cheap and plentiful, 6 lugs...not as much. The 8 lug also has the disadvantage of the Eaton rear end, which is very limited in aftermarket parts.
So I'm leaning toward fixing up the C10 to sell.
Though it would be nice if there is someone whom could chime and provide a compare and contrast from having been behind the wheel of both a C10 and C20 of that Gen.
Regarding the rear end gearing, if I keep the C20, I'll either have to replace the rear axle or rely on wheel/tire size.
Thanks,
Rick