I bought the "Akust Rubber Anti-Vibration Grommet Ring with #6-32 Screw 16 PCS" from amazon and they kinda worked. I had to put the grommets on the case, then screw in the screws.
These ones are smaller and would probably work well "Akust Rubber Anti-Vibration Grommet Ring with #6-32 Screw (16PCS, Blue)"
I bought the blue ones off amazon, and they fit better and were easier to install. I think the black ones probably did a better job, even though they were harder to install.
I have exactly the same case. Spent a lot of time on support line, trying to understand them that this is a technical question. Support staff told me that it is presale and they not allowed to do commercial things. They are sure that as I want to upgrade my Optiplex 5080MT, then it is presale. Period. I never had such kind of support from well known brend. Do they really want to pay their staff for such kind of spending time? Is it so difficult to give clear information about spare parts? Unbelievable. Still have no luck with these parts. I will try Amazon or Aliexpress instead of Dell.
Get them to send an email with the pre sale wording.
That way when you escalate you can show the wording to management that they are not helping post sale.
I went with the black ones due to larger grommet so it wont fall out if bounced during shipping.
Blue Grommet Screws
Black Grommet Screws
Akust Rubber Anti-Vibration Grommet Ring with #6-32 Screw 16 PCS
Brand: ZUO XI UTOPB