Since I have an M1078 with the highspeed gears and a locker in the rear, I’ll chime in with some thoughts. A Detroit style locker in the front would be a bad idea. It would lock up too often when you didn’t want it to, which is a bad thing in the front. As far as needing a different transfer case for lower gearing, I haven’t found it necessary. I’ve found it’s still geared low enough for what an rv should do. Also I don’t think I want to wheel an rv and try to keep up with the jeeps. If you want to, you had better have deep pockets. Also the fmtv cabs don’t fair so well in roll overs or head on’s. On the engine choice the 3116 doesn’t have huei, is simple and can be turned up to 300hp with a different turbo. The 6x6’s already are turned up. Also the 3116’s don’t have all the emissions stuff. I love my truck, but it’s like a boat, ha!! (Bring Out Another Thousnad). My best advice is if you get one, do all the work on it yourself as you will learn valuable skills and see what tools are essential to carry with you. And have a baseline knowledge to fix in the field. Highspeed gears make cruising at 60 drivable. Past 60 and things get a bit lively. But passing a military convoy at 70 and seeing the look on the commanders face when you pass is priceless. Also only the Goodyear tires are rated past 55. One great thing about the A1 trucks is the exhaust brake! I’m in the process of collecting parts to weld one on mine.