Sounds like you already narrowed it down for yourself by deciding not to change rear or transmission.
Do you have a 235 or 261? The 261 would be useful for the little extra power to pull a higher gear.

About all you have left then are taller tires and an auxiliary transmission.
A Spicer 5831 would be a good option, and pick one with an OD ratio to suit. The parking brake needs to be on the back of the last transmission, not between them.

There is something called a "Ranger torque splitter" that offers overdrive before the main transmission, sandwiched between engine and transmission. I don't have any experience with one but I hear they're generally well liked.


•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-