It’s the plug used to tie in power supply on a bus when installing a wheel chair ramp lift The factory connector separates and connects to each side of this

its honestly not part specific to anything, as those are just varying sealed connectors, we use these on cars and various custom wiring projects when we want to keep moisture out wires this probably was a custom setup to run maybe lights on a trailer or truck, such as indicators, brake and park lights etc

References:

https://www.summitracing.com/parts/msd-8170

Reason:
There are 30 of these. They do not look custom made. It does resemble the 1 connection tip that you referenced but not the other 2.

It’s the plug used to tie in power supply on a bus when installing a wheel chair ramp lift The factory connector separates and connects to each side of this

References:

https://www.braunability.com/us/en/commercial/wheelchair-lift-product-applica...