KB1 1948

one thing you can do is jack up the rear end, both sides, support on jack stands, chalk the front tires, put in neutral. put a mark on the sidewall of one of the rear tires near the tread. get underneath and put a mark on the drive shaft. have a helper turn one of the rear tires on full revolution, and count how many times the drive shaft goes round. If it goes round four times and a touch you likely have the 4.11 gears. this is not scientific, but a good approximation of what you have.

Thanks Resto

Because of the way that a differential works and the possibility of the rear wheels not turning together, especially if the person turns one wheel,the chances of getting a proper ratio is nearly impossible.
With the truck on a flat and level surface, mark the driveshaft and one tire. Have someone count the turns on the driveshaft for one revolution of the tire. Make sure that the tire pressure is where it should be for easier rolling and accurate counts..

Thanks Nikki. Presume you are saying to have the truck on the ground and roll it counting the turns.

That would be a yes. There were three differential ratios offered for the KB1, in 1948. They were, 3:72-1, 4:18-1 and 5:11-1. IHC built 23,552 KB1 in the Springfield plant and the Chatham, Ontario plant built 1152.
In 1948 IHC built 100 ARD-626-Fheavy duty trucks for the Russian government oil industry.

So, looks like my KB1 was made in Springfield, Oh.
Thanks

Because of the way that a differential works and the possibility of the rear wheels not turning together, especially if the person turns one wheel,the chances of getting a proper ratio is nearly impossible.
With the truck on a flat and level surface, mark the driveshaft and one tire. Have someone count the turns on the driveshaft for one revolution of the tire. Make sure that the tire pressure is where it should be for easier rolling and accurate counts..

on an open differential, the right tire is usually the drive wheel. jack it up like I describe and turn the right tire, etc.

You are incorrect. You need to do some research on how a differential works. Try You Tube for a start.
I just checked You Tube and there are dozens of good video explanations.

This is about the best teaching tool out there. Play with one for a few minutes and you'll never forget how it works. I wanted one sooooo badly when I was a kid but never got one. I did make a functional differential out of an assortment of other gears and parts though. Not pretty, but it worked.

nikki is correct, neither wheel is the drive wheel. The carrier (grey part in the picture) has no idea which axle (black parts) it is driving, so to speak. Each axle will take its turn depending on conditions (and that right there is the whole point of having one). The spider gears (white parts) will compensate for differences in axle speeds as required. On a totally flat surface, in a perfectly straight line, and with tires of the exact same diameter (that's a lot of theoretical ifs) then both wheels drive equally and at the same speed. In this condition the spiders do not rotate at all with reference to each other. That is the same as if a spool or locker where in use - but only under that one ideal condition. Very neat stuff. Maybe Santa will bring me one this year, finally...

You are incorrect. You need to do some research on how a differential works. Try You Tube for a start.
I just checked You Tube and there are dozens of good video explanations.

don't need to. I have done the procedure I outlined before, including on my 1949 KB1. it works. not scientific but gets you a close idea.