Ranchoth I know what you mean - the big two-letter code on the tails.
For example, an F-16 with SP on the tail is from Spangdalhem, Germany. An A-10 with DM on the tail is from Davis-Monthan AFB in Arizona, etc. The last jet I flew in the Air Force was the T-1 out of Laughlin AFB, TX. Our tail code was XL. Most people ask “What the heck does XL mean?”
In Laughlin’s case, the Air Force just happened to be putting tail codes on all training aircraft when Laughlin AFB had it’s 40th anniversary. So, the XL is actually Roman numerals for “40” commemorating the 40th anniversary of the base. Of course since then it’s been corrupted to mean “Excel” - ie people at Laughlin EXCEL at everything! Please.
Anyway, I did some googling on Wheelus and found quite a bit of stuff, but nothing that would indicate that they ever had a specific tail code. In fact this site has numerous pictures and discusses tail paint that reflects the squadron, but no tail code. The jets seem to adhere to the early jet days of “FS” or “FU” on the fuselage and squadron colors on the tail.
Sorry I couldn’t be of more help…