TS 6 position chip. (only 4 tunes on yours, but has enough memory for 6) Could be any of the custom tuners, or it could even be TS themselves.
The actual chip is plugged into the PCM. You can see the PCM from inside the cab of the truck. Look to the rear of the e brake pedal and you will see a grey box looking thing in a black plastic sleeve. That is the PCM. You should see a wire coming out of it and if you trace that wire, it will go back to the knob on your dash.
If you remove the chip, it MIGHT have an indication of who tuned it. Although I wouldn't bet on it. (They will all say TS on them, it doesn't necessarily mean it has TS tunes though)
Read
this and you will see exactly what I'm talking about.