the rear-end on this 69 chevy doesn't have replacement parts from the supplier I called.
my truck engine has to rev real high to run at highway speeds.
I jacked the truck up to check the gear ratio but the strangest thing happened. I had to rotate the wheel 8-9 times to get the drive shaft to turn 1 time.there is no noises during operation.what is going on here?

what will be the easiest and economical differential swap for 1967 - 1972 3/4 ton chevy? I would like to get a lower 3 ratio for daily driving but mantain the hauling weight of the 3/4 rear-end.
thanks  

i would leave the g4eears alone and put a 700r4 overdrive automatic. if not then get a rearend out of a newer truck the builld sheet might still be under your front seat and it will tell you which gears you have. also if find a newer truck use it to tell what gears it has.