you would have to cut them out of the 4x4 front chassis rails and weld them into the xr4i chassis rails! it would be easier to modify the exisiting rails. best thing would be to find some one near you who has a 4x4 and take a look at the chassis to see what is to be done. i think the transmission tunnel has to be widend to accomadate the transfer box and front prop. that could be cut out of the doner car and welded in