I have 2 Tivo HD units. 1 has blown out one of its tuners we'll call it Tivo "A". The other has a failed hard drive we'll call it Tivo "B". What I have decided to do is take the hard drive from the Tivo "A" and replace the hard drive in Tivo "B" resulting in 1 working Tivo. I'm sure this will result in a call to TWC to come out with a new cable card. I'm curious as to what identity the hard drive swap will make Tivo "B" assume. I guess the question is what determines the identity of a Tivo the software or the hardware?