[Tx Firefighter]

Four lug wjeels are 68 and newer, or perhaps some aftermarket parts fitment.

Beginning through 67 got kingpin front end. 68 and newer were ball joint. A quick way to differentiate between the two without getting too technical is to look at the front shock absorbers. Early, kingpin front ends, used shock with eyes at top and bottom. Later, ball joint, front ends used an eye on the bottom and a stud at the top.

On the rear, do you have IRS or swing axle transaxle ? One has straight tubes from the trans to the wheels, the other has definite axles with CV joints on each end.