I have yet to have an owner of the newer style WSMs tell me the thermo was on.
Seems to me the closest was 20 degrees. Yours looks to be off 60+ degrees.
Not sure if there is a direct replacement, but you could use a uni-bit to enlarge the existing hole and add one of the other Tel-Tru thermos.
My Boys: Joseph (EI); Andrew (EE); Daniel (EE)
My Toys: 11 WSMs (B, C, E, DH, DA, EZ, DZ, EO, DU, DR, EE/DU); 5 - 22.5" Bar-B-Q-Kettles; 2 - 18.5" Bar-B-Q-Kettle; 3 WGAs (EZ, DE, N); 2 SJPs ( DR, DR); 2 Smokey Joes (A, K); Genesis Silver C (DU); Brinkman Cimmaron; Chuckwagon Cooker; .
"For when democracy becomes tyranny, those of us with rifles still get to vote"