Ok, I know this sounds crazy, but I'll share my 2 cents. I had 4, Tel Tru BBQ's analog dials as you are wanting to use. I placed them in above the grate locations on a custom build. The temps were always off because you can never really get to the center where it's much hotter than the probe can reach. Then after a month, the moisture / humidity made them un readable. I ripped them all out, HUGE waste of money. I'm still pissed, and that was a year ago. They looked good, but that was it. Then I did the unthinkable. I went to home depot, in the BBQ section and bought one of those metal turkey fryer analog thermometers for about 4 dollars. The one with the really long stem, not sure but 10-12 inches approximately. This is the best probe on the market, the stem reaches the center of most every pit, is very accurate, can take the high temps because is for a turkey fryer, and is dirt cheap. If it breaks, 4 more dollars, but it's lasted a year already, better than my 60 dollar probes that break for sure.
" Don't ask me who I am " CENTRIXS