Drivetrain HELP????
 

I have a 1970 two wheel drive. It has I believe a saginaw 3 speed manual tranny in it and Im not sure what the rear end is. The Truck wraps out the rpms badley at highway speeds Ive looked everywhere around here for a 4 speed for it but no luck. I was wondering if just changing my ring and pinion would do the trick and make my truck better at highway speeds. If so does anyone know what ratio to go with and how hard is it to change out. Thanks all for your help.
Also how do I figure out what gear ratio I got now.
Thanks again
Tim
Mechdawg:flag: