Just to add a comment, as I see the "can this be upgraded to TMCC" question regularly:
Anything within out 3RO world can be upgraded to TMCC (or PS2); essentially, this GG1 is a model containing 2 DC can motors hooked to some kind of reversing unit. Remove these electronics - unplug or even cut the wires - and install the command boards per the instructions and off you go. Lighting/smoke functions are available on the new boards. Sound plugs in. Experience makes the next one easier. And the next one...
So, when you see a loco that you like but it doesn't have the command you want, you do not have the excuse that it cannot be "upgraded" - heaven forbid you should have any reason to not spend your money. Nah - go ahead.
I added ERR Cruise Commander to a 1950's brass Mikado (Lobaugh?) once. It already had a DC (open-frame) motor, and off it went.