https://www.amainhobbies.com/savox-sa1230sg-tall-digital-steel-gear-servo-sav-sa-1230sg/p234358
you can use just one of these in a Tmax, just use one of the steering ports.
https://www.rcplanet.com/traxxas-wiring-harness-for-rx-power-pack-revo-tra3035/
here is the switch
you'll want a servo...