I have been trying to read up on the difference between Rev B and A in the forums. But, I am still a bit unsure. If you get an A.....do you just need to buy that $30 part from 3dr and then it is the same as the B? Or, does the B have completely different hardware? I ask because I bought three of these things in the best buy sale. 2 have the circles on the box, one does not. So, I think I got two Bs and 1A. Trying to decided if I should return the A or what? Thanks for any help!