The Talking Machine Forum — For All Antique Phonographs & Recordings

I was wondering why one cast iron base has cut outs under motor and another has no cut outs . Are they different model bases or are they just earlier/later version ? Any help would be appreciated.
Dan

Pictures...?

Here are some pictures , they have different #’s on bottom of base too.
the solid one has 4507 3
the others 4507 6 and 7