Stupid me. Mower is ready for the deck to go on. I had some yard work to do and this was the handiest mower to use. When testing I had strapped the engine to deck belt on the deck hangers and left loose on the engine pulley as there was a belt guard band around it. So what happens as I'm finishing I see belt smoke. Somehow it got caught in the pulley and it cut a nice slit into. Kicker is that when I removed the belt it turned out that the belt guard was an easy removal. Had I only realized that I would have removed the belt before. Problem is belt 66071-61720 is showing as 67" in some places and 68" in others. The belt on it is labelled LB 67 but measured 67.5 on my roll up the wall technique. LB 67 is showing as 68". In fact stens has 258-068 (5/8" x 68") replacing kubota LB-67 so I guess I will order a 68.
https://www.stenscanada.ca/258-068-belt
But to add to confusion on belt size. The stens 258-068 replaces kubota LB-67 and Yamaha LB-67. Stens 258-067 does not replace anybody's LB belt. Stens 258-066 replaces Yamaha LB66. I would expect it to replace Yamaha LB65 ie stens number 1 higher than Yamaha, as Stens 258-065 replaces Yamaha LB64. No wonder people get belts that don't fit.