Troy, before you change out the thermometer, is yours not working ?
Troy.
I installed a 2" River County therm, RC-T2, in my Jumbo Joe. What I did was install it through the middle of the top vent. Here. (The RC-T2SS looks good also, it's stainless steel).
1. Remove the screw or rivet from the vent.
2. Enlarge the hole in the vent & lid with a step drill bit to accommodate the [SUP]1[/SUP]/[SUB]4[/SUB]" NPT thread of the therm. (I would also suggest to install a fibre washer between the vent and the lid). Install the supplied nut on the inside of the lid.
3. Tip: When drilling the hole in the lid, enlarge the hole just enough to get the first two or three threads on the therm in. Then slowly screw the therm in. Because the the threads on the therm are NPT, it's tapered & enlarges the hole as you rotate it in. This ensures you don't drill the hole too big & you also get a nice snug fit.
I'm sure I saw a thread where someone replaced the OEM therm with an aftermarket model, & made it fit the OEM bezel. I'll have a search & post back if I find it.
Edit: Joe F did the mod you're looking for here.
Hope this helps.
Troy, here is some more information.... Measuring Temperature In The Weber Bullet