About 10 years ago I put a sae bell housing on a 96 dually, put a eaton 6 speed on it, then put a brownie behind that. It was 2wd of course, if I remember I re geared the rear to something that sounds crazy tall, like 3.08 or something, maybe taller.
The brownie shifter came thru floor where normally a t case shifter would have been.
It was like driving an old Mack.
The truck would make 370hp all day. It wasnt a slouch to begin with. It took some driving to figure out what gears split well with others but in the end you could tow whatever you felt like With that truck, and I think top gear at 80 was around 2100.00. Before with zf5 and 4.10 70 was like 2400.00 rpm. If I was driving at 65, and wanted my rpm to be 2300, no problem, or 70 and 2100, etc etc. you just shifted to put rpm where you wanted.
It was the fully synchronized model ( can't remember model) but after getting going it shifted better without clutch. I drove it just like a big truck.
The brownie is a 4 speed, so you could technically shift all this stuff till the cows came home . But that isn't how you drove it.