This is my point, as is Roadkill's: you cannot get by "cheap" with just a few parts for a lift, you need a complete kit to keep the steering geometry in line like it was stock. The drop brackets do lower the frame mounting points for the radius arms and axle beams, but also require longer coil springs AND shocks for the front. When you drop everything down 4' or 6", the steering linkage attachment at the gearbox must also be lowered using a drop Pitman arm. You cannot just use drop brackets with the rest of the stock parts, or use taller coil springs with the stock parts, since you alter the geometry to the point beyond it's ability to steer. With a 4' or 6" suspension lift kit, you do not normally need to lengthen the stock driveshafts. You still need to check that you have enoughendplay in the slipjoint for safe operation, though, as the actual amount of lift will vary a bit from one kit to another. AS for the difference in a 4" and 6' kit, the axle beam drop brackets often have two holes, so the same ones are used in both kits. The ends of the axle beams bolt into the top hole for a 4" kit, and the bottom hole on a 6" kit. The 6" kit will have longer coil springs and shocks for the front.
With all of that said, if you want to fit 35" tires as cheaply as possible, then a 3" body lift is cheaper. It does not change the steering geometry from the stock set-up, it just raises the body higher off of the frame. There's still some labor involved in relocating the radiator fan shroud and bumpers, as well as extendingthe steering shaft and any transmission and t-case linkage.
The third and "free" option is to trim the fender openings to fit the larger tires. You will need to remove about 3" around the openings, which is about where the flared part or lip begins. This is what I did on my 78 Bronco to fit 38's. JSM84
