I tried two nearby stores with no luck.The WD 8TB drives are back on sale. This time for $160. Supposed to be a RED inside. The two I bought previously were indeed REDs inside.
I keep getting the error message from the NAS that there is a fan failure at startup, yet fans are both working. It's quite annoyingly beeping at us each time.
I checked the TS-831X logs and there have been no warnings for a few months. I think it was resolved by a QTS update in August or early September. There was nothing mentioned in the release notes though.The fans are typically pretty easy to replace, though I've only had to do it once.