I had a set of the Smittybilts for 73-91 on my truck a million years ago. The brackets on the left bolt to the forward hanger for the rear spring, and IIRC the ones up front go to the frame.
Getting the back ones aligned was a challenge, as I recall. I'd take your truck to them, and put the one up against the spring hanger and see if the front lands on the frame in a place that you can drill without having to remove everything.
-- A