Join Date: Dec 1999
Location: Winston Salem, NC
g5067, I had this exact same problem in my car. I have a '67 Camaro that was originally a 6 cylinder with a powerglide and it still has the original 6 cylinder 2.73:1 ten bolt rear end. When I bought the car, the speedo was not hooked up cuz the gears were all wrong. The car has a 350 and Th-350 with non original 15" tires now. It took many trips to the local chevy dealer and several gears before I got the right one. You MUST replace the gears with a matched set and the metal output shaft PG gear WILL NOT fit on the output shaft of the TH350. I tried it. But all hope is not lost. You need to go to your local chevy dealer and get somebody that is somewhat helpful in the parts department. They have a book that crossreferences all your car's specs and tells them which speedo gears to order you. Give them the transmission type, the rear end ratio, and rear tire size and they can look up the gear. You'll probably have to hound them for them to do this for you, since these guys don't like to flip through books. It turned out that for my car's mismatched specs, I needed a gearset out of a 74 Camaro or something. But, the speedometer is as accurate as can be now. Good luck to you.