After I primed my cab, I had it sprayed by a painter with an oil based paint. Use a couple of thin coats versus one coat. If your cab is free of defects, I think that this is the way to go.
If you use a roller, you might want to thin it a bit, so it levels out more evenly. However, there will be spots that the roller won’t cover by itself.
If you use auto paint, make sure that you prime it with a product made for wood and metal (I’m not sure how well auto paint will perform on bare wood).