squarebody rear bumper

i have an 80 cc dually i want to put the suburban rear bumper on it but i can get the 81 and up rear bumper at any junk yard but i cant find any 73-80 suburban rear bumpers
so will the 81-up rear bumper fit? it looks like it will???

It's a different style (meaning it won't match your front bumper), but as far as fit goes, it will work fine.

Keep in mind the Suburban brackets are different from the truck brackets, so you'll have to do a little drilling (on the bracket) to get it to work, but it's nothing major.