Basically four different options here. 3 sp "Brownie", 4 sp "Brownie", GV OD Unit or US Gears OD Unit. Truck is "potentially" 1992 Chevy Kodiak LoPro, 5.9 Cummins (mild), AT545, 60" sleeper, 9' flatbed, 245/70R19.5 tires, weight ~10,000#'s, pulling 10,000# gooseneck horse trailer or equivelant (sp?) size camper. I don't know what ratio the rear end is but the two options I found on the heavy truck parts websites was 4.33:1 and 4.8:1. For the sake of discussion we'll assume it's a 4.33:1 since the truck started life as a 366 gasser. Using http://www.ringpinion.com/Calculators/Calc_RPM.aspx and 245/70R19.5 (33.5") to figure out rpm's and such, 55 mph gets 2,389 RPMS's and 65 mph gets 2,829 rpms. Fine numbers for a gasser but way to high for a diesel. I would like to get down to the 2,000 rpms at 55 and 2,300 rpms at 65. I've never had one or used any of the above so I'm looking for some input for the guys who have. Here's the questions... Can a "brownie" be mounted "divorced"? I'm thinking about where the midship bearing is. Will a US Gears unit hold up to heavy towing? With a "brownie" is it possible to leave it in OD while cruising around empty then just leave it in Direct for towing? The AT545 has enough gear reduction (3.45:1 1st) that even with it left in OD (20% reduction) still leaves you at 2.76:1 still deeper than a TH400's 2.48:1. Where do you even find the old brownie boxes and is there anyone left to get parts from? So, enough rambling, on with the ideas and suggestions. Hoping this will spark some ideas and help anyone else who is thinking of something similar. And remember "THEORETICALLY" is the key word here. Just thinking ahead, don't even have the truck yet.