dieselcarpenter

How do I find out what rear/front axel I have, how many splines, bolts, inches, gears, locker/limited slip? what gears are best for all prupose, (tow/haul, highway, offr-road/hills, and impressing the import guys)? Never dealt with axels or diffs, I want to run 35" tires eventually, And increase hp/trq (atleast enough to win a tug-o-war with my father-n-laws 98 f-250 crew with the no-power-stroke

JD730

If you have the original hood with the tag still intact it will say what was originally equipped with your truck.
Dana 60 front, 3.55 or 4.10, pass side diff, king pins, # of splines????, I don't know.
Dana 70U rear, 3.55 or 4.10, 32 spline, open or Power Lock limited slip.

There should also be tags held on by 2 bolts on the diff covers if a PO hasn't lost them, there will be the ratio stamped on there as well, with other numbers that decode to what exactly is in that axle build.
Worst case you have jack it up and chalk the wheel and drive shaft and spin it counting the rotations.

I have 3.55 in all the older trucks and wouldn't want anything else. Biggest tire I run is a 315-75-16, which is around 34-35". No problems turning them.

wannadiesel

Since it's not a dually and it has the 5 speed, it's possible (but highly unlikely) that the truck has 3.07's. They had to be special ordered, but they were available.

dieselcarpenter

thanks,which ratio is better for what?

wannadiesel

3.54's are great all around, but for real heavy towing the 4.10's are best. 4.10's are not so good for highway cruising with an empty truck, that's where 3.07's shine.

jughead

a-men on the shine.