I have Offroadxdeign SAS kit in my 2000. They are a very reputable company. I also have DIY4X’s, and again very reputable company. I haven’t installed DIY’s kit yet, but like it lil more over ORD. They have different holes to adjust where the axle sits, or to accommodate different length springs. As for axles, getting to be slim pickings. Best is Ford, depending what you want. With 35s a Dana 44 will be fine. Need 78/79 Ford F-250, or 73-77 1/2 ton, but sill need to modify some stuff. Do you wanna stay 6 lug or 8? Goi g 6 is more involved. To run 35s, need roughly 6” of lift. The kits give 3”, so need a 4” lift spring. Many options out there for it all!! Here is my truck with stock front springs, and a 33” tire.