I would guess your lift on your truck either used new leafs or a new block? If it used just new springs then yeah you could add the block from 4x4 f150. From what I have seen the stock 4x4 block is 2 inches. If your lift on your truck came with blocks, I have not heard good things about stacking not recommended so in that case just get an add a leaf of about 1.5 to help level. You going to need some new ubolts as well. Post a pic of your rig!
07 STX V8 RCSB 2wd. EdgeEvolution. 20'' OEMs. 2'' GF shackles. 3" SI/SO Magnaflow Magnapack Catback exiting to 4" Mag Rolled Tip 5% tint. Gotts Mod w/ K&N drop in, PTM side views--->