Well, I managed to fix my tick. I have owned this DII for about a year and have driven it about 13,000 miles. It now has about 94,000 miles on it. The previous owner had replaced the wires and plugs about 5,000 miles before I bought it, and the short block had been replaced with a new one when it had 67,000 miles on it. Just before I bought it, a shop had put in new exhaust studs. When I got it, there was an exhaust tick on the passenger side so I replaced the gaskets and reused the nuts the shop had used which weren't like the OEM ones at all. The engine was quieter, but there was still a slight tick in the drivers side. It was always there, warm or cold, and followed the engine speed so I figured it was probably an issue with the valve lash from the rebuild. Well, the exhaust nuts loosened up again, so I pulled the y-pipe down again, reinstalled the gaskets with a light coat of Permatex Copper RTV, and installed a proper set of exhaust flange nuts. The engine sounded good again, but that light tick was still present. I checked the manifold for leaks with the engine running and noticed the wire to the #5 plug vibrating. Looking closer, I could see the plug moving too! The plug was out maybe 3 turns! I replaced the plug with a new one and torqued it down. I checked all the others also and found the #7 plug was loose too. With everything snugged up, the engine is now free of all ticks.

I guess the lesson here is to take nothing for granted and make sure you check over all of the basics before you start chasing problems. Just because work has been done recently doesn't mean it was done correctly. The engine ran great and never threw any codes but was obviously not running properly on two cylinders. The new plug torqued down fine and the tick is gone so I guess I didn't waste the head but it could have been much worse.