Weird brake attachment

[J33pman]

Hi, I picked up a 62 C10 as a parts truck, and I plan to convert it to a trailer once I pick it for my 63 C10.

I noticed something odd attached to the rear brake line on the right side--apparently a former owner tapped into the brake line and ran a splitter off of the line. The flexible line continues to the axle, but another solid line runs under where the bed was and exits right above the license plate. There it turns back into flexible line with a coupler. Apparently this was a farm truck and he pulled something that utilized the braking system of the truck.

I'm wondering what its correct nomenclature is, where I could get this item, and whether I could use a setup like this to utilize the existing drums on the trailer via the braking system of the pulling truck to have trailer brakes.

Thanks!