Well, it's fairly faint at idle, gets louder under load. Seems to go away when clutch is depressed but I'll have to drive it around the neighborhood a bit more to nail that down. Climbed under the truck with it running last night, seems to be coming from around the flywheel housing, but I can't quite locate it. Think I'll pull the transmission hump and see if I can better isolate where it's coming from. I don't think it's coming from the block, which I assume is Good News, if true.
It's a knock, I don't hink it's timing related, almost sounds like something is a bit loose. Talking about sounds is tough, but after reading around on here, I'm kinda wondering if the flywheel doesn't have bolt or two loose.
I've got a very slight oil leak somewhere in the drive train, I think - I know my original valve cover leaks - I have an aluminum replacement on hand along with a fresh gasket, need to replace that and clean the engine up to see if what I'm seeing on the bell housing is simply run-off from the valve cover. But I do have to replace the e-brake pads (at least) so I'll be digging around under there soon enough.
Hoping it's 'just' a loose flywheel...