I don't have a direct answer to your question. However, there are two versions of speed control model year 2001. At some time during the model year, the speed control was changed from the servo type used model year 2000 and earlier to an electronic speed control. My guess would be that the change occurred at the same time the rear drums were dropped and the tailgate trim was eliminated (the 2001. 5 Ram). Or possibly the change happened when the assembly line ran out of parts for the servo speed controls. Date of manufacture may play a part in answering your question.