This is how you calibrate your speedo, just change your gear to one with different # of teeth.
11-70031 Speedo Cable stock for Early Bronco
11-70032 Speedo Cable for stock speedo to Atlas t-case for Early Bronco
22-00121 Speedo cable for stock speedo head to VSS 63" long for Early Bronco
22-00122 Speedo cable for stock speedo head to VSS 83" long for Early Bronco