The Weeden 647 was only produced for 6 years (from 1927-1933). I haven't come across any discussions about a bunch of variations, (and I don't own one yet; but I do have a very nice Weeden 648). Here is the description from Ken Trobaugh's Weeden Book. This book is still available on a memory stick. It is the best reference work on all things Weeden.
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The information to contact Ken is below:
kennethtrobaugh@yahoo.com
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