majorsjeffrey,
Hopefully I can offer some help and advice here.
Regarding the body mounts, they are the same for 4x2 and 4x4. Some of the 67-72 4x4 trucks actually use different cab mounts than the 2wd trucks, but not the 60-66.
Regarding springs:
Your stock springs are 2.5" wide all around. Fronts are 44" long and rears are 52" long. Later years have varying widths where the bushings are installed, but they all taper down to 2.5" where the axles bolt on. Later years also have varying spring lengths.
Rears: Technically speaking any rear spring from a 4x4 from 60-76ish will fit. They are all 2.5" wide all around and are 52" long. In the mid-late 70s some time they switched to a 56" long spring. Spring pack thicknesses and number of leaves and amount of arch vary from year to year and from 1/2 to 3/4 to 1 ton, so mix and match wisely.
Fronts: No stock front springs will work for you from the later years. Only the aftermarket springs, and only up to 72. 73 and up used a 47" long spring, whereas 72 and down used a 44" long spring.
You are in luck, because all the aftermarket spring suppliers make springs that are 2.5" wide all around, and they use wider bushings to make up the difference. What you want is aftermarket springs from a 69-72. You will have to do some custom fabbing/machining with the bushings to get them to work in your factory spring hangers and shackles. This is most easily accomplished by using poly bushings in my opinion. The 60-66 factory bushings were all bronze bushings with greasable bolts that had hardened bearing surfaces. Bronze is expensive compared to poly if you are going to make custom replacement bushings to fit aftermarket springs.
If you plan on keeping the stock springs, LMC offers replacement factory type bushings. I don't know how good they are. I've gotten some good and some not so good stuff from them before.
All of this info may just confuse you more. Let me know if you want to know more.
