7720 Battery Train Set - LEGO instructions and catalogs library
Train Battery Box Car with Switch and Red Wheels and Cargo Doors Pattern on Both Sides (Stickers) - Set 7720 (Undetermined Type) : Part x488c01pb03 | BrickLink
LEGO 4.5V Train 7720 Battery Train Set from 1980 Vintage Set! review - YouTube
Diesel Freight Train Set, battery : Set 7720-1 | BrickLink
7720 With real lights - LEGO Train Tech - Eurobricks Forums