Replacement air brake knobs?

[arrover]

My brother has a 1985 GMC 6000 with air brakes. The air brake knobs are in poor shape and I was thinking about replacing them for Christmas. Are the replacement knobs universal? I can find lots of replacement knobs but I'm not sure if they will work on his air valves. The air valves and knobs have a logo with a "BW" inside of a diamond. I think that is the Bendix corporation. Will all of the pin style knobs work?

Also, any idea where I could find a replacement knob for the two speed rear end?

Thanks guys!