How do you change the speedometer gear on a 4x4 88 Comanche for bigger tires?

To change the speedometer gear on a 1988 Jeep Comanche with 4x4 for bigger tires, first, determine the correct gear ratio based on your new tire size. Remove the speedometer cable from the transfer case, then unbolt and remove the speedometer gear housing. Replace the existing gear with one that matches your new tire size and reinstall the housing and speedometer cable. Finally, test the speedometer to ensure it's accurate.