The earlier version but have had both and can say just like the earlier version 675/2025 vs the later 2025/675 the earlier is a quieter smoother running engine .
Why is that? It has been said that the machining standards loosened later on, its been my observation those early version 2026, 675 , 2025 vs the later ones its true.
My opinion those early ones were indeed the Zenith years for Lionel spur geared motors.
Bingo @Dieseler, I couldn't agree more that the early 675s,2025s and 2026s were by far the smoothest and quietest running of this genre of engines. Not sure why but perhaps they used a different motor altogether but loosening up the machining standards certainly could have caused the difference. The later ones don't run nearly as quiet and smooth as the earlier versions.