Hoof. Thats an obscure one. Ford? or Detroit aircraft company or one of is subsidiary's like Eastman or Marine Aircraft? Been a few diesel A/C engines, but I can't think of any US...or any air cooled radial diesels. In fact, the only radial diesel I had ever heard of was a huge russian 56 cyl liquid cooled unit intended for use in an icebreaker.
"The meek shall inherit the earth....six feet long and six feet deep!" - Lazarus Long