I have a 08 f150 2x4 with 6" lift on it. Rear end sittign about 2 inches lower than I like (I added bilstein 4-6" adj shocks up front to get an additonal 2" or so of lift). Anyway my question is can I take the stock block off a 4x4 (junkyard) and use it, will it work? Also how tall is the stock 4x4 block, 1.5" or 2"?

 

Stacking blocks isn't recommended. Either buy a bigger block, or get an add a leaf.

 

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!