Hi, I'm in the process of restoring a 66 and I’ve just painted the gear box. I used hamerite black satin paint which i mixed 2 to 1 with thinners and sprayed with a gun. I could have used a brush but didn't want to see any brush strokes. The preparation needed was a full clean down with paraffin to remove gearbox oil and road mud then clean with brake clean fluid in a can followed by a wipe down with panel wipe which removes oil and dust before painting. The end result looks great!