going to be tough to weld them if you cant clean both sided of the weld location. There is a clamp on bung available that uses a hose clamp to hold the bung in location.
That looks just like the single probe EGT that was in my airplane when I bought it. They work fine for leaning and reaching peak EGT at altitude at WOT.
My 260 HP 540 C.I. air cooled 180 degree opposed flat six cylinder Lycoming would start to shudder and miss a little bit while manually leaning it out before reaching peak EGT, the cockpit gauge read from around 900 F up to 1600 F is what I'm remembering now, I would lean it to peak and then richen it up 25 to 75 F from peak. That made the ride smooth and it would keep the 16 spark plugs clean as well as not waste precious 100 LL Aviation gasoline.
