The models you describe are all series 1 DirecTivos. They are no longer in production and it is unlikely you will find one in a retail outlet. The Sony SAT-T60 and Philips DSR6000 are still available through some on-line satellite dealers. The DSR6000 is currently offered only as a refurbished model although you may get lucky and actually find a factory fresh unit from some dealers. 2.5Xtreme will only work on these models.
The series 2 DTivo has not been released for sale yet but should be out very soon. The newer models will not be hackable, at least for the time being, until someone figures out how to do it. You can, however, still perform hard drive upgrades on these units but not much else. There may be a way to get a bash prompt that will allow other utilities to be developed and installed but it's a wait and see proposition for any of this to happen.
Please don't PM me or any other members looking for personal assistance. You'll do better by posting (after you've exhausted the search feature, of course) and taking advantage of the collective expertise of the membership instead of a single individual that may or may not be able to help you. Thank you and enjoy your stay at DDB!