I have quite the bastard of a 1964 Land Rover 109. It has been converted to a 4.3 vortec motor and nv4500 5 speed. I believe the transfer case is original. As is, first is unusable and even reverse is annoying. The truck was upgraded to Salisbury axles with disc brake conversion on all 4 corners. I'm not sure what year vehicle they are from. What is the easiest way to swap for 3.54 gears and source vehicle? Thanks in advance.