Is there a code on my 76 Corvette that tells what gear came in my car? Someone has replaced the rear end gear I think because on the interstate the speedometer shows 85 MPH at around 3,000 RPM. Actually I think it is running about 65 MPH because other cars are passing me. The speed limit is 70. Also the temp guage runs a l hair over 200 on the interstate. The guage runs about 170 around town. I would like to get the right rear end gear back in so my speedometer will be accurate and so the tach wont run so high. It drinks gas this way too. Thanks