Im kinda laughing at the phrasing used in the OP... "recycled old computer, or new updated model".
Not sure why the OP thinks that if HW2.5 (which is the same thing the car was delivered with) has to be "recycled, old computer". It could be "new, HW2.5 the same as was delivered with the car computer".
In any case, OP if you are still interested in this, if you search this site there is a post somewhere that details what part numbers HW2.5 and 3 are, and where you can remove some stuff to get at the computer to look at it if you so desire. Of course, as was already said, if you purchased FSD, you will end up with the new computer anyway, and you wouldnt want it right now in my opinion.
It seems that tesla has HW3 emulating at least parts of HW2.5 (changes in recording codecs in one of the software version released), and I personally dont want my HW3 upgrade until there are features that only work on HW3, AND those have been tested a while. Perfectly happy waiting into next year around this time if it takes that long.