I believe the 2wd front crossmember unbolts. Pull that out, use the spring hangars, shackle mounts, and engine mount crossmember, and suspension/swaybar from the 'burb. The framerails are suposedly the same, its just a matter of bolting the 'burb parts on the Blazer(use grade 8 bolts...). AFAIK you have to change the rear leafspring hangars/brackets too, or lift the rear suspension cause the 2wd had different brackets.......
lots of work? I guess....... If I had the extra time and the parts on hand I'd go for it tho. I don't understand why nobody just bolts in a 2wd crossmember in a 4x4 K5 if they want a hotrod lol
Good luck with it & post pics!
-John