Anyone here familiar with “brownie” transmissions?

I’d like to regear the ol turd, I mean Ford, for better climbing but I don’t want to give up my fuel economy. Way back once I saw a guy fitted a brownie transmission to his Ram 3500 and I was wondering if anyone on the board here could point me in the right direction:

1. where to buy one
2. Are they universal?
3. How to install one


Thanks y’all hope you’re staying busy out there



edit: I found out the other day the previous owner had an Allison MT643 swapped in. OEM Ford 9inch rear end

 

I saw those and the Gear Vendor O.D. Units. Gear vendor only rates theirs to 25klbs, which the truck and trailer weigh about 18.5k. Couldn’t find anything on the advance adapter site but I prefer to stick with the Brown-Lipe/Spicer transmission

 

Thank you for the info, I’ve found a few for sale online. I’d prefer to buy it in person tho.

I’m definitely going to have to do some custom driveshaft work to get it on, but it’s very doable. I’ll post an update once I’m getting around to installing

 

you think the entirety of the gear reduction (overdrive) will be lost to rotating mass? That hadn’t occurred to me.

the one I had found is a 3 speed. 20% underdrive, direct drive, and 20% overdrive

 

2000 F650, Cat 3126.

I may be wrong, here’s a pic of the plate. All I can tell for sure is 4.33 gears