I’ve read a bit about a S10 5 speed swap but I’m not sure that’s my answer. Overdrive available? The S10 5 speed (also known as a T5 transmission) IS overdrive in 5th gear. Ratios vary between 0.86 and 0.72 depending on year. A 0.72 OD would get you to 69 MPH at the same engine speed you are currently running 50 MPH IF your 235 could get back to that RPM with the higher speed gearing and IF you had the intestinal fortitude to drive it that fast.
'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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