In Reply to: Staying home is fun work-some tractor stuff, some OT posted by John in Mich on May 25, 2020 at 09:01:00:
If the mounting holes for the Hupp could be accessed without turning the rear gear, you have about a 25 MPH top speed, similar to Sherman. If you had to turn the rear gear, your top speed should be about 15 MPH with a lower under-drive speed.
If the main shaft had 5 splines on it, then your running the newer version of the Hupp. The older versions ran two splines and easier to break the stationary gears inside. The older versions were also easier to hang between ranges when shifting. The newer boxes had upgraded shift forks.
Best of luck with your toy.