I found a Gates Super HC belt to replace the IH cadet belt. Its number #3VX315 and its 3/8" x 31.5" long. Its only a dollar and change cheaper than the IH belt but i can get it the next day from Mcmaster Carr. Its a 3/8" wide at the top but its the deeper vee into the groove. Its a thicker belt rather than a narrow belt.
Gates Super HC 3VX315 3/8" x 31.5" $10.29 each and this is a cog belt for flexability.
Dealing with McMaster Carr is so much faster in shipping its worth it.
I been using the narrower 3/8" belts to wear in the pullies again from them being rusted from sitting for a longtime. When i first purchased the tractors i run a wire wheel to clean up the rusted vee belt pullies but using the cheap vee belts is the final clean up on them. Once the pullies are clean i can install a good quality belt and forget about it. This has also been a problem with the PTO pullies and the mower deck pullies too. I notice it takes a few belts to clean up the vee grooves in the pullies again. Its from the PO letting them sit outside rusting.
Now i'm going to work on all the rest of the belts to see what the gates belts will interchange with the IH belts. Now i know the IH belts are thicker than normal vee belts.