It should be a 70mm x 70mm x 25mm, either a 2 or 3 wire connector would work, just use the red and black, ignoring the extra wire.
There's another thread around here somewhere where replacement fans were discussed recently and various models recommended or not.I have a SA TiVo Series 2 (TCD24008A) that the fan is shot in (noisy). I tried hitting the fan with some 100% silicon spray which helped some, but I assume the bearings are shot as it's still quite noisy. It's not the HD as I just put a new one in it, and this thing is making way too much noise for just the HD.
So, can anyone recommend a replacement fan that fits without modification? Preferably from Newegg?