rear bumper question

I plan on swapping my rear bumper because when I bought my truck (89 crew cab dually) it had a solid steel homemade bumper on it that weighs about 200lbs if not more. I wanna put the original one back on like the one in the pic below. I got to looking at it and the brackets are not going to work so my question is what brackets go on it? Where could I find parts for these trucks? Seems like everyone has left them out of their catalogs.

ok well I tried uploading a pic but it didnt let me.