Help! Need to Change Overdrive Gear Ratio in Spicer 7231D Auxiliary Transmission

[mspina6732]

You may know that the Spicer 7231D from Dana corporation is a 3 gear over, under, and direct auxiliarytransmission. It'd a 1960s unit and I have parts service manuals. Unfortunately, neither gives the information in a way I can understand to change out the overdrive gear ratio from tge current .89 to something closer to .75; I need more top end speed. Can someone tell me how to select and procure the gears I need?

 

[alfio]

You may know that the Spicer 7231D from Dana corporation is a 3 gear over, under, and direct auxiliarytransmission. It'd a 1960s unit and I have parts service manuals. Unfortunately, neither gives the information in a way I can understand to change out the overdrive gear ratio from tge current .89 to something closer to .75; I need more top end speed. Can someone tell me how to select and procure the gears I need?

Did you ever get any info on this? Thanks

A.