Here you go: http://www.earlycj5.com/technical/sp...ng-conversion/
You will end up changing all 4 spring hangers and all 4 shackle hangers. The front spring hangers attachment points sit inside the boxed section so they are a bit hard to get to. Since the rest of the frame is open channel on the 75 they are not too hard. You will bolt the new shackle and spring hangers in place with grade 8 hardware, mount a spring to make sure they are straight, tack weld them, remove the spring, then finish weld them. Some people do not weld them but that's not recommended especially with the flexibility of the intermediate CJ frame. You will need new shackles (rear CJ ones seem to be the most recommended), replacement u-bolts, and you will have to widen the holes on your spring plates (search the forum on this as the holes need to be moved in 2 directions for both the wider spring and thicker replacement u-bolts). Of course you will need whatever springs you are going to use with correct length brake lines and appropriate length shocks that fit a CJ. The Old Man Emu 2.5" YJ spring is highly recommended and if you dig around on the forum you can find the part number for the correct CJ shocks. Some people keep the 1.75" wide axle perch and some cut them off and weld on new 2.5" wide ones. If you were wheeling the hell out of the jeep I would change them otherwise I would leave them be.