the only major difference between 2wd and 4x4 heads is the piece of ally on the exhaust side for the 2wd turbo damper. the 4x4 does not have this. however, some people cut it off 2wd heads. obviously a 4x4 head is beneficial in that it will be newer and the ally will not have softened, but if you are using a 2wd exhaust manifold you need some way to mount a turbo damper to help support the weight.