By the time it was all said and done, it was a 91/3/4 deck belt.
Had to remove a belt guide (small OD metal rod) the other shop had put that was all in the way. It was L shaped. (not even on the parts diagram) Once I got that off, it freed up about 1/4 belt tension.
Now everything is back on. I mowed about 1/4 acre, engaging and disengaging the belt around each corner. It stayed on. And I didn't smell anything. Soooo, I guessing it's all good.
One thing I didn't like, was the two idler pulleys the other shop put on. They were plastic and didn't have much of a lip on them. I told the customer about it, but he says to just leave'm and he'll get the other shop to put the right ones on it. The OEM ones are metal and have higher lip.