Richard,
The part is as followed: 2002 FORD RANGER 2.3L 140cid L4 FI (D) : Cooling System : Thermostat MOTORCRAFT Part # RT1157 {#1S7Z8575AG} 1S7G-8575-AG.
I had the system flushed and yes it needed it, and after being flushed it overheated again.
Still searching the web for answers.

Tony