I used one for years and my truck bed never rusted!
Beware! These things are top heavy when empty. They dont just tip over, they flip UPSIDE DOWN. If you get this one it will work fine but take this advise: Cut a five gallon bucket bottom off about 6 inches. Screw the bucket bottom to a square piece of plywood, jam the porta quick into this base. I used to keep a five pound dive weight in the thing and it helped a little.
This was back when the new vac style pumps weren't available yet and the Jabsco was all we had.