I am planning a 500 Cadillac motor swap. I have read most of the posts covering cad motor swaps. I have a few questions and would like to get some opinions from the gurus who have been down this road before... I want to build the ultimate go anywhere anytime truck, road, rocks, sand, mud, trails etc, etc... and make good gas mileage. 1. bop th400, Why not just use this tranny? pros + cons 2. T-case, What is the best behind this combo and why? Your opinions on doublers and underdrives as well. 3. R&P gears, What is the best ratio for a 38 inch tire and the afore mentioned t-case. Remember, I want good (15mpg)gas mileage.