motor mount identification

I recently purchased a 1973 Flying Scot (my first FS) and I'd like to install a small motor. From reading the recommendations on motors in these forums I have learned that there is a new motor mount system. The FS I have has a mounting system but it's not the new system. I assume I have the old style I hear about but I would like to verify that it's not a 3rd party mounting system or perhaps there might be more than one type of "old style mounting system". My transom has four bolt heads standing out from the transom about 1/4 inch. The 4 bolts form a rectangle, longer wide than high. Does this sound like I have the mounting bolts for the FS old style motor bracket? Is there only one old motor mounting system? I appreciate any information along these lines. Gonzalo