Mossyrock,
Not to be evasive, but it depends on the type of tumbler that you have. Being that you are going to be tumbling 'WET' the center column of the tumbler bowl (the part that the threaded center mounting rod goes through) has to to be higher than on most tumblers. Any liquid leakage will most likely end up on top of the motor - not good.
I have a Midway tumbler and I bought a Lyman 600 accessory bowl, Lyman P/N 7631399, which has the center column about the same height as the rest of the bowl. This works great when tumbling 'WET' and it only takes about a minute to exchange bowls.
I suppose that you could install a rubber gasket on top of the center column of a standard bowl but I just didn't want to take that chance.
Two hours of tumbling cases shot with real BP and they come out looking almost as good a factory.
This is a good investment.
HHW