cummins 6b5.9 alternator failures

update: with the help of 2 of our members, I have a fix. Tim, aka 96bounder, suggested that the 15SI has marginal bearings for an 8 rib belt pulling a big fan. That wasn't my main problem, but it turns out that my alternator's bearing were shot, and that was the noise that had recently started coming out the back of the rig. Tim recommended a 22SI, or 21 or 19SI. Mr. Wizard had sent me his ESN so that I could look up what parts Cummins used on his rig that had room for a pulley. When I first looked up, I was dismayed at how much was different. But when Tim suggested a 21SI, I remembered that's what Mz Wizard's ESN calls for. The brackets from Cummins to change over were only ~$40, and the J180 mount seems sturdier and eliminates the need for the back support brace, so I decided to go ahead with the 21/22SI. My local alternator shop had a 21SI in stock and a core they let me borrow for fitting, so that's what I now have. The reason that this setup seems to work is that the pulley is set further out from the fan that it was with the 15SI, so the belt tensioner pulley passes above (or behind in terms of the MH orientation) the alternator fan. So all my hardware is mounted with stock Cummins hardware. Since I didn't change the belt tensioner to match Wizard's, I had to measure the appropriate belt length.
Here's what it looks like now, with a glorious fan attached


and another view from above

It seems fine and charges well. The one regret that I have is that I 'upgraded' to the HD belt. The HD belt is pretty stiff, and so the tight bends from packaging are still bouncing the belt tensioner up and down. I'm hoping that the heat from the 1st trip will get rid of the belt's memory, but still afraid that every shutdown will put different bends that will bounce the tensioner. I'd prefer to wear out the belt, not the tensioner.

Thanks RV forum for all the assists
Gary