The heads passed the gasket test. Looks like it's the block. But outta time tonight. I noticed something though. I think the bolt hole in the block may have a little angle to it. When threading in the problem stud it doesn't seem to be an issue until maybe 1/4-3/8" below the fine threads. I can see where it touches and rubs the head as it's threaded in. There's also an increas in resistance while threading it in. Now I'm concerned about angles and clamping forces. Time to replace the batteries and grid heater relay in my pickup.. Thanks B3RE!