Have been searching ebay in quest of a new GP9 ish diesel that will work with my 027 siding switches. Have narrowed it down to 3 and wondered if there was any difference in the motor performance in them. 1. MTH 30-2117-1 , 2 precision flywheel motors. 2 Lionel 6-11863 ,pullmor motor. 3. Lionel 6-28874, dual maintenance free motors. They're all made around 1997 and very similar in price, Appreciate your input.