This is a “coupling adapter” which allows to couple a trailer to a truck or sometimes a second trailer behind a trailer.
Coincidentally this also works to mount a Burder trailer behind a NIC truck
The model is only 32mm long not sure if this works for every truck
I printed with
layer hight: 0.15
supports: on (build plate only)
infill: 15%
The author hasn't provided the model origin yet.