The 4BT is going to weigh around 750 lbs and the 6BT is going to be around 950-975 lbs. I don't know how stout you can make a MII suspension but it could be the limiting factor for the larger diesel. This could be a neat swap with the right parts and pieces. Like Dave said it only takes time and money. Good Luck.
SimS
Last edited by SimS; 04/09/2014 1:25 PM. Reason: typo