issue of overdrive light indicator staying on occurred a day or two after having transmission serviced (fluids changed). Transmission also began slipping in and out of gear.

tranny started slipping took and had it rebuilt at a respectable shop, picked it up drove 21 miles it slipped again and the O/D light started flashing, took it back they said T/C switch was bad relaced that same thing again, has now replaced the new drum from the rebuild with another, brake pedel switch, wiring harness, vaule body, and is now replacing the mess air. Which may or may not fix it. Does anyone have the answer for this.

Thank you,