"I have several hard drives I have obtained through the rears "
I see why you'd ask the question .. if I obtained them through the rears I'd be hesitant to do it again myself <grin>
/Just funnin' with ya Earl
If you can download the upgrade, why not just install them over existing? You can install the new version and RTs over a previous year's hard drive without issue in my experience. It may take a little bit longer, but it'll work.
Your only real risk is hard drive failure, but I personally have had no experience with PGMusic drives failing over the years.
They work for a very long time in my experience.
All that said, I keep the current working copy of BiaB on a separate internal drive, and the most recent external hard drive is my fail-safe fallback to a recent point in time (I think of it as a snapshot; if my main drive fails I can get back to the most recent year's version pretty quickly)
.. and even run the program from it in a pinch if the failure occurs at the worst time
I've been fortunate in that I've not needed to do this, but now that I said it out loud I probably jinxed myself

@RustySpoon#
PG actually did offer the upgrade on a thumb drive a couple times, and I used that method. Worked fine for me at the time.
That was an 'upgrade' version though and not the whole enchilada, so you got the new stuff, but not all the stuff