Thrift store find! Is that 6990, the space monorail? it sure is! : r/lego
LEGO+Space%3A+Monorail+Transport+System+%286990%29 for sale online | eBay
Lego Classic Space Monorail | Lego space, Lego space sets, Classic space
LEGO 6991 Unitron Monorail Transport Base | BrickEconomy
LEGO Space Unitron 6991 Monorail Transport Base with instructions, RARE | eBay
Amazon.com: LEGO City Space Deep Space Rocket and Launch Control 60228 Model Rocket Building Kit with Toy Monorail, Control Tower and Astronaut Minifigures, Fun STEM Toy for Creative Play (837 Pieces) :