Question of Compatability

You can NOT lash up an MTH engine with a Lionel engine.

However if you run them separately you can operate both n same layout

Steve

From what I remember, when trying to lash up TMCC and Legacy locos, the TMCC loco has to be assigned the number 1 or lead position.  I've only ever run lash ups of Legacy locomotives, so I cannot comment further.

Andy

I have had some luck "dumbing" down the Legacy engine to TMCC. Then running both units in a Lash up. However, its a roll of the dice. With the truck systems being updated some of the engines just run smother, or have a different gear ratio.

I usually run the TMCC items together and the Legacy items together.

Not a good Idea, from what I have heard they run funky lashed up.

turn off the odyssey on the legacy engine, place the tmcc and legacy engine about a foot apart.  start running them, if the space stays pretty much the same you are good to go.

odyssey thread

I cannot run any Lionel engine with speed control, i.e. Odyssey with a regular Lionel TMCC engine. Even with the Odyessy off the TMCC engine runs faster.