GRAVELY 8163-B had B&S single 16, however so does 8163-G, but 8122-G, 8123-G, 8179-G & 8199-G are Kohler. 816S is a B&S.
8162-T, 8163-T & 8183-T have Twin Onans, as did 816T & 818T.
The 1st Professional: 12-G, 16-G, 18-G & 20-G were all Kohler. KT equates to Kohler Twin.