I have been meaning to put my 12in thermometer in my UDS. I have around a 6in thermometer in there now and I am getting mixed readings between my two digital ones and my analog one. I was hoping to get the probe closer to the middle and maybe that will help some of my issues.
I use the Eastman Outdoors models in both my UDS (two of them in Meatdawg) and they have always yielded me accurate results. I've tested them against my digital probes various times. Now I just rely on them without reservation . . .
I have 4 2" holes as top vents for my UDS. As it turns out, my 12" deep-fry thermo sits perfectly in a hole. So I use 2 thermos. One of them I stick into one of the pieces of meat on the top rack. The other one I just leave resting through the vent hole down into the center to get me a perfect reading on the upper grate temp.
It's cheap and it works great until I can afford a better setup. I hope to get an ET-73 and do the range mods someday but thats more than I have in my whole smoker so I'm hesitant to do so; especially since money is pretty tight.