doc it is possible,, we put a 3,91 out of a Challenger, into a E55 .,, mounting bolts were added, axle replaced, hubs were replaced. a crossfire limited TCM was used, programmed to 391, we used the limited tcm because the guy wanted to keep his E55 tcm and differential with 265 gears for a spare,, we had a limited tcm laying on the shelf so we used it.,, it runs great.. jim