So i have an 83 firebird with a swapped 350 and turbo 350, the car originally came with a 4 cylinder and i think a 200r4? I dont think the guy that swapped trannys swapped the speedo cables, becuase the speedo only goes up to 25. My question is am i right that a wrong cable would give me an inaccurate reading, and would a mechanical 700r4 cable work the the turbo 350?

 

Transmission has a gear where the cable hooks up. Could be a broken or wrong gear.