Brass distributor gear?

Pretty sure the 496 is a distributorless ignition with coil on plug

When I make hard runs I trim the drive out under load to gain bow lift at WOT. Could that be over loading the thrust bearing? The coupler is heavily lubed with the Merc specified lube.

No, but if there is too much grease in the coupler packed in at the front it can overload the thrust bearing.

Yes mine is an EFI set up. Thanks for the thought though.

Rage, Check to make sure your engine mounts are still tight. I have seen the 3/4" nut back off on the pedestal mounts. This would let the engine torque up and put pressure on the rear main thrust bearing. Just a thought... The ones I have seen were the port side.

Hey Jon, thanks for the suggestion! I need all the help I can get.

valve spring shims....

Yes, I have the copper flash coated shims but they have hundreds of hours on them and the copper was mostly gone before this spike in copper in the oil occured. Thanks for the input.

Rage- Are you going to tear it down?