Bump.

Put an IR on it after some driving this afternoon at the shop. ~200?F inlet vs. ~350?F outlet. Seem about right to anyone here who knows? Google is full of wildly varying numbers, so I can't be sure.

I didn't think to smack it with a mallet to check for anything loose inside, BUT, I know running too rich could result in a melted catalyst, and the engine has always run-on when I shut it down, AND there's always soot on the rear window, so... [i]could it be the temp sensor for the gauge works, but the one for the carb doesn't, forcing the truck into enrichment more often than it should be (thus the reason the gauge never really gets up to operating temperature), and that enrichment is killing / has killed the cat?

Damn if these things aren't all related...