Ditto on what gmc248 said.
Get the tallest tires ya can, 8.25X20 or 9.00X20.
The 2 speed rear axel was NOT just for low speed hauling power!
It was super for using as an "intermediate" gear between 4th and 3rd downshifting on the big trucks. Works great to keep up rpms on uphill hauls.
When the big ones were going up a hill you could switch from 4th gear High to 4th gear Lo and it would maintain the optimum rpms.
4th gear, with Lo on the 2 speed differential, was NOT as low as the 3rd gear dif. in high!
ex: 4th Hi= 6.13:1 rear axel ratio
4th Low= 8.10 "..."
3rd Hi= 10:48 "..."
So going 4th Low is better at high speed downshift than 3rd high.(same holds for downshifting from 3rd to 2nd, etc)
The big trucks truly purrr optimum cruising at about 45-55mph and will run A-ok at about 57-59mph on a level road.
Not bad for the heavy load hauling ability!
More than 60mph and ya really have to concern yourself with stopping power in the old brake system that was designed by Chevy & GMC to stop better with a load than empty.
It's the RPM's and not the MPH on the old trucks. Gotta love a tach!
In short: get tallest tires and get the 2 speed differential working good and thats about as good as it gets. Beats the heck out of driving most old 1940's, 30's, 20's trucks....its just slower than todays interstate speeds, but heck it's an antique!
Ps: If ya can shop old junk yards for a late 40s' thru 1950's++ Chevy shorter wheel base school buses they most likely have the lower 5.43 or 5.14 rear axel for the bigger trucks as these were rated from 10500GVW to 12500GVW, similar to 1 1/2 tons. Some cab-forwards also had better high speed gears.
john
1952 COE 2ton
1947 Coe tractor
[ 11-11-2001: Message edited by: lil' johnny ]
