3:55 gears to 323 gears
Our family factory-stock special order 1971 Plymouth Road Runner with G60-15 Goodyear Polyglas tires, torqueflite, and 3.23 open 8 3/4 differential would run exactly 3,000 RPM at 70 MPH, so around 2,500 at 60 MPH. A four-speed should show a little less slippage than a torque convertor equipped vehicle (lower RPM). Photo is my parents old RR that I found recently via Facebook & FBBO:
Our family factory-stock special order 1971 Plymouth Road Runner with G60-15 Goodyear Polyglas tires, torqueflite, and 3.23 open 8 3/4 differential would run exactly 3,000 RPM at 70 MPH, so around 2,500 at 60 MPH. A four-speed should show a little less slippage than a torque convertor equipped vehicle (lower RPM). Photo is my parents old RR that I found recently via Facebook & FBBO:
