hey dunl, i say do it, you will love the rusults. hps4evr, that is a 231 doubler to a d300 in that pic. for the right person, that would be a very cheap doubler to build, even if you have to get a custom shaft made. there are a few places selling the whole kit, and i am pretty sure one could just by the parts needed seperatly. mad rooster comes to mind as does the fox-box of of island 4x4.