This is a 3 chain engine which may be why the chains look HD, the IMS to crank was redesigned to a gear type chain instead of sprocket type in the 3 chain engines. Finding an IMS took forever, and then 2 in one week on Ebay. I've seen several others since, but none with a gear drive. I considered pinning the shaft, but weighing the risk benefit (loose pins in the engine) and my novice status as a machinist, I'm staying away from that. The old IMS shaft took it on the chin and now has 0.015 wobble in the gear. It's dead. Maybe I can stand it up with a base under it and make it into a trophy. That is the original tensioner arm. The IMS gave up the ghost at idle there was only one chip out of the plastic on a tensioner that looked related to the failure. There were metal chips embedded in all the tensioners. They will all be replaced. And I'd be honored to have admin use that first pic as an intro!