Here is what I did to my '57 GMC V8. It is a Sun Supertach II that I refaced using an Xacto knife and a GMC instrument face decal kit. Then I flipped the switch on the back of the tach to 4 cylinder mode to make 4,000 RPM on my V8 = full scale. The Hydra-Matic upshifted at 3850 RPM and there was no way I was going to take it past that engine speed with a 3.08 rear gear in 4th.
'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.
