The original belt is a salsbury Number 704142.Good luck with that one.These trike were the predessesor to the john deere gator.Took that belt to a dealer.Nope,dont have it.Do a search here.motocycle has some good info on belts.
I have the Sasquatch, photo is in "my photos", I will try to put in in this post.
These machines are Real Beasts.
The Commuter Industries, Grainger and Sasquatch machines were the forerunners of the John Deere AMT (Early Gator). John Deere bought the rights to these machines in about 1984-5 and started producing them as the. AMT Gator. Commuter Industries had both 3 and 5 wheek machines. John Deere only made 5 wheel machines.
I remember I also had a hard time finding a belt for my machine.
I see the other machine has a Jason belt on it. Yes that may work; but the Jason belts are not power sports belts; that is an industrial belt. Somehow the cords are different in them. Yes, I know they work; but this type of clutch depends on the belt to give optimum performance.
These machines are not hard on belts, so the Jason would hold up under normal conditions. If you can find a snowmobile belt, to transfer to that number; that would be a high performance belt.
I played with the belts and every manufacturer a few years ago; and it is really intricate.
Thinking about what motocycle said and those that run the 5L300 belt. A 5L300 belt is the same as a B27 ve belt. It is 27 inches around the outside. Looking at the chart for TAV belts on this site, I would think that this belt would work.