There are some people with reservations about working with chromate primers, similar to the problem getting honest chromate treated hardware. For more info, consider looking at forums about painting aluminum boats or airplanes. eg.
http://forums.iboats.com/forum/boat-...e-marine-paint
http://www.practicalmachinist.com/vb...r-coat-214482/
http://www.aircraftspruce.com/menus/cs/primers.html
http://www.awlgrip.com/support-and-a...rt-advice.aspx
I haven't used any of these products but was investigating becaused the 15cwt radio body is aluminum. When the time comes, I may need to draw on the knowledge in the aircraft refinishing shop at work.