so ya my title says it all thanks for any info

 

Well, in the 80+ range, front axle ID is pretty simple, measure the hub diameter. 3.25" = D44. 4" = D50/D60, so ya gotta look underneath to see if it bends in the middle.
I would assume the hub diameter is the same for earlier models.....

 

Look at the axle, There is a stamp. That will tell you

 

One of the easiest ways is to check the size of the cover bolts. 1/2=d44 and 9/16= D60

 

x2! Easiest way to tell them apart.

 

X3 i always carry a 9/16-1/2 combo wrench when i check out a truck, not everyone knows what they have up front for an axle and every now and then you unwittingly hit the D60 jackpot, so much has been swapped out over the years on these trucks a D60 could be under anything.

 

Pirate4x4.Com - Extreme Four Wheel Drive
Here man this is the eaysiest way to tell haha. This page has a ton of info way to much to list.
'79 fourdoor