In consideration that all of the used glass will be of the same approximate age as the one you have, reckon when they'll get hazy around the edges? Which is one reason a "fresh/new" one would make more sense. PLUS getting them to install it, with a fresh rubber seal, too.
Reason is that if they damage it, THEY replace it. If you do that, it's your pocket being emptier.
The main thing I'd be concerned with is the thickness of the new glass being what the earlier OEM glass is. Which relates to the seal being able to do its job as it should.
On the rear glass, first look for any signs of rust in the lower corner areas. On YOUR car and the donor vehicles. Don't need to cause any issues you aren't ready to deal with!
If you get new glass in the front and rear, will the side glasses look worse in comparison? Do a good, thorough cleaning of the inside surfaces with warmer water and a cleaner. Might need to put some towels down at the bottom of the glass, too! Then wipe with hot, damp towels as the final clean-up function. Use a newspaper and cleaner to clean the outside surfaces. The newsprint ink is supposed to polish the glass for a nicer finish.
Having spare "glass" is always a good deal to do . . . until they get broken/damaged just laying around. YUK!
Just some thoughts,
CBODY67
IF you're worried about the date code, that's an easy deal, as I understand it. PM me.