I just called my Cat dealer (Wheeler) and they said that 5L6672 is available and they can get it. price $166.91
Hey, Thanks for checking in. I also managed to locate availability at an online Cat parts site. I guess I talked to the wrong parts guy at NC Machinery. The set seems to be in someplace called Monroe, maybe a Cat warehouse. Adding WA sales tax and shipping, the price is a tad over $200. Once I check and can confirm no internal compression leaks into the cooling system, I will order the belts. The old girl was the victim of a pocket knife cooling system drain once upon a time and the block remained full until a Montana winter managed to create a few more drains. Here is a short YouTube flick about it: https://studio.youtube.com/video/1TWKccvjtaM/edit
All the Best.
Jeff