Curtiss offered the Hawk 75 with 20mm and 23mm Madsen underwing pods. (Super-late reply, but I thought I might as well make it easy for anyone coming across this topic.)
I don't have an information yet about weight, but the cannon apparently badly degraded performance and the pods were removed from most or all aircraft. Information is very, very thin. I'm hoping someone in Thailand, or with contacts, can eventually find something.