John, I think about the same thing almost every day. I am really into jeeps and the off road seen as well as the focus. There is an off road buggy called the Rhino (www.rhino-offroad.com
) that uses a Honda engine mounted sideways in order to utilize two solid axles in the front and rear. The trans axle is obviously locked with a spool with lockers in the axles too.
The part that I am hung up on is the loss of efficiency in the drive train. Building front and rear cross members is not a problem, but what to use for pumpkins is the question. Basically anything in the Dana crowd is most likely too heavy and will kill anything but a turbo focus. I bought a for 8" last year and then ditched it because I realized the the pinion is mounted too low to the point is looses a 3% efficiency over a 8.8.
I do not know enough about other cars in order to figure it out right now, but I am thinking the center chunks out of a subi with custom axles and hubs.