Just because a Hammond Organ looks like B-3, it does not mean it is. There are a few important things that make a B-3 authentic. It's 4 legged cabinet of course and more important, it's serial number and components that match the number. An alarming amount of counterfeit B-3's without serial numbers seem to be showing up on e-Bay lately. Sometimes a seller may not know that a real B-3 needs to have it's serial number intact because they were conned when they bought it. They then unknowingly try to sell it as authentic. But, more alarming is the fact that there are people selling fake B-3's that actually know what they are doing. Taking a Hammond 3 series organ and putting in a B style case without the proper identification tag, does not make a Hammond organ an original and valuable B-3. If you are going to pay a high price for an authentic B-3, do not be fooled by an organ without a serial number plate in it. All Hammonds including B-3's had a serial number from the factory.  This being said there are also many other details to be sure of authenticity. If there is a plate, go on to other details. Make sure things like the color of the transformers (black or silver) matches the year of the plate. Wood cheek blocks or plastic? A-100's are commonly used in  a B conversion organ. The wire harness that connects to the preamplifier will be much longer than an original B-3 harness. Check things like that. You can go to a Hammond Age Determination List on the web, to check all these details before you buy. Know what you are looking at. There is absolutly no excuse why a plate should not still be with the organ if the organ is original. If you are not sure, that plate will tell you if it is in fact an authentic B-3 (or B-3 cabinet) and will also give you the original serial number which will tell you around what period of time it was made by The Hammond Organ Company. If you are told the plate was removed for any reason, continue your search for a real B-3 if that is what you are really looking to purchase. If the plate is there, check for other details as well. This is really just common sense. You will never recoup your investment on a Hammond B-3 that does not have it's ORIGINAL serial plate intact. Also beware of organs that are said to be totally rebuilt by a professional tech. Get the information about exactly what rebuilds were done and who the tech was before you spend your money on a Hammond B-3 that may in fact be a counterfeit. There are many places on the Internet to tell you who is qualified to rebuild Hammond organs and who is a hobbyist claiming to be a Hammond organ technician. Always do your homework before buying any classic musical instrument as an investment. You are you own protector when it comes to investing wisely. There is nothing wrong with buying a B-3 that was assembled from other Hammond organs and parts without an authentic serial plate as long as you are informed of that information by the seller and fully realize what you are buying is not an original Hammond B-3. I have built many B-3 conversions that were great sounding, great looking organs. These were sold as 3 series Hammond B conversions. NOT B-3's. Buyer beware and always purchase from a dealer or seller who has credentials he can show you. The Internet has become a wonderful place to an open world of buying and selling. It has also become a great place for the clever to mislead an uninformed purchaser. If you let yourself get ripped off by a con artist who uses all the right words to sell you a fake item, it is your own fault and there is little you can do about in today's Internet world. Do your homework first.