There's one on eBay (Completed Listings); they were made to be "command upgradeable"
as you know, so you might be able to find the Lionel radio board/antenna kit - try Lionel's
parts department. It's a plug-and-play. If not, Modern Toy Train Parts has the ERR kits.
Straightforward upgrade.
The loco is handsome, NYC-ish, well made and modern. With a plastic tender body the
antenna ia a 60-second installation. If I were limited to sub-scale steamers (boy,
that would have saved me money!), I'd be all over one.