8 3/4 ring gear change for optimum low end performance

Treblig said

This is what I use....just plug in the info that you have (tire size, MPH, etc) until you get the RPM/MPH you want.

Gear Ratio Calculator

Click to expand...

Thanks Gil....I found this one too...on the spicer site....it includes overdrive but not lock-up. Gets close enough for a real look.
Spicer Engine RPM Calculator