YepLook to see if it has a hard steel brakeline going to it. If it does, it's very old.
I bet if you look under the hood, the big resistor (a flat plate that looks like it has some springs attached to it) is out there too. That is old. If I remember right, the lever moves when you step on the brakes and to adjust it, you twist the knob. I would get rid of that thing if it were me. They are all solid state now.
The only problem would be, if for some reason you would loose the truck brakes, you would have no trailer brakes unless applied manually. Example would be a rotted out brake line leak.What would your reason be for getting rid of it? If I reconnect the wiring and it works what's the problem?
Should have asked.
What size and weight of trailer are you gonna pull?