ok, that was vague. I am looking at a few International 4900 33,000 gvw trucks dt530, Spicer 10 speeds. most have glad hands, protection valves, etc for air trailer brakes, however I have came across a few than only have air truck brakes. Is it hard to add a trailer valve, and run air brakes for a trailer?

The trailer only has air brakes, not suspension.

Thanks

 

Not hard at all. Requires a few parts if the truck wasn't designed to be a tractor, but not hard.

 

Like Chaikwa said, not hard at all. Actually easier than electrical brakes.