You are correct. That manual does not give a direct reference to your situation. All I can do is give you the best explanation I can. You are on the only forum that pays any attention to the Lawn, Yard and RER tractors. Hardly anyone collects them and therefore, no one discusses them to any extent. I'm just trying to make you understand why there is so little information available. Secondly, the J81 snowcaster is listed to be used on the earlier 107, 117, 108 and 118 models that precede the 116. I had no idea that it would even fit your tractor and that's part of the confusion with the Belt Guide manual.
In reviewing that manual, my suggestion is that you go out and buy an 88" x 1/2 belt that is definitely Kevlar reinforced. In the alternative, contact Brian Hildreth and order a belt from him. His contact info is in the FAQ's section under Dealers who are Members.