https://www.fractal-design-shop.de/
I used this site to get some upgraded 3.5" trays to suit the bolt pattern on 6tb+ drives, about 6 months ago. But, they are pretty much out of stock of everything atm. That may just be use to covid, or it may not.
There is a way to set an auto notification on the part your after, though the wait might be months to never.