610-9845-160.
The truck frame was made to accept a roller pick-up assembly, grounding strap and hall-effect sensor for the magnet on the splined axle.
It was used on the TMCC Aquarium Cars (6-19845 Whale and 6-19868 Shark) and Animal Cars (6-19846 Giraffe and 6-19850 Lion).
TRW