BINGO....I use John Deere blitz black on everything from frames, axles, mufflers, and everything in between. It's a semi gloss and has the perfect amount of gloss to it without looking like things have been spray bombed.
My F550 was nasty when I got it with rust and just a crappy looking frame and such from being a plow truck in it's former life. I used my high pressure, high heat pressure washer and washed the under side real well and once it dried I sprayed the frame, axles, leaf springs with the JD blitz black. A year later, lots a mud, snow, and grime with only getting washed when it rains it still looks decent. If I would of did prep work it would still look like day one. But I was in a hurry to get the truck on the road.