So I will be working on a 78 F150 making it offroad ready
it has a 3 in body lift on it already, but I want to add 4 in to the suspension and all the lift kits I find have the add a leaf for the rear.
my question, is the add a leaf the way to go for the rear or should I go coils all the way around and make a 3 member and bracket?

 

I guess it depends on what you are trying to do. For my old truck, I used Rancho 3" coils up front, which are a little stiffer than stock. In the rear, I used 2wd F250 leaves with an additional leaf from my parts truck, and then made drop brackets to eliminate the factory (and Rancho) block.

If I had it do do over, I would buy deaver coils and run 2500 chevy 63" leaves with a shackle flip. The rancho coils were too stiff, didn't flex and the rear was a lot of work, comparatively speaking. Most of my flex was from the frame, not the suspension.