[CC69Rat]

I have seen narrow and wide axle housing's in the 70 model year. I think it just depends on when the truck was built. (early builds would have possibly gotten the more narrow rear housing)

Lay under the truck from under the back bumper area. Have the wife / a buddy hold a tape measure on the inside edge of one rear brake backing plate. Measure the total length of the axle housing from one backing plate to the other (a.k.a. Plate-to-plate) it will be 57" for the later housing, and 55.5" for the early housing.

At least this way you'll know whick one you have in the truck (who knows, it could have been swapped over the years) 70 model could be 6 lug and the wide housing (I had one once upon a time) but I have seen the narrow ones too.

When you buy your 5 lug axles, the narrow housing (early) will be 30.5" long if you measure from the mounting surface of the wheel to the end of the splines. The later ones will be 31 5/16.

For example, say you find some for sale and you know you have the narrow housing.. if they come from the 71-72 model year and are 31 5/16 surface to splines.. they wont work. A lot of times you'll find original 5 lug for sale, but chances are they are the wide ones. If you had the wide housing.. youre in luck.

Go ahead and change your bearings and seals too while you're at it. It's pretty easy. If the pin bolt breaks off when you replace the axles, PM me, I know the fix for it.

IMO, I'd just get what you wanted from Moser that way youd know they're new and in good shape. If you find good GM ones, of course they'll be 40+yrs old. Just something to consider.

Welcome to the board by the way!