When did Lionel go back to free-wheeling locomotives?

I think Lionel does it on and off occasionaly - my Vision Hudson and Southern Crescent have free-wheeling, but both of my SD40-2's and GS-4 Daylight don't. I think it's more common in steamers.

I actually thought the non self-locking gearbox was standard in the LionDrive diesels and the "better" Legacy locos.  I'm surprised to hear you say your Daylight isn't freewheeling.  I understand that the early FEF and the M-1b were.  I also know the Milwaukee S-3, the 2-10-4 Texas, the Vision Hudson and the 11212 Nickel Plate Berkshire were.  The 4-6-0 "Ten Wheelers" were as well.

Personally I like it, it's a good feature.  The locos move freely at slow speeds, but there's enough friction in the drive train that in conjunction with the speed control electronics, the locomotive doesn't run away downhill.  Cool!

So to answer the original poster's question, based on my experience, most of Lionel's better offerings have been free-wheeling since about 2008.  -Ted

"Back driveable" gears have pretty much been standard since the first legacy offerings, back in 2008 as Ted mentioned. These are especially helpful in a "lashup" as they allow the slower loco to coast.

I'm surprised to see your ESE loco has this feature, I didn't know it was ever offered in a TMCC loco, I've never had a TMCC loco with this feature

I always liked the back drivable, or free wheeling drive wheels on all engines. It's a pluss from trouble shooting switch cross over issue to young kids who love to push the train by hand.

I am not a machanical engineer but I always thought the advantage of the locked grear assemblies was that they provided better pulling on slow start ups of heavy lodes. Is this correct?