Nope, that is not the correct gasket for service kit SK182-65, which are the gaskets for the flush-fitting cap, AKA "Killer Caps." That link looks similar to the gasket for the later SK182-85B "raised inlet" cap, but it's not the correct part number, so use at your own risk. McFarlane does sell PMA'd replacements for the raised inlet cap. If you have those, I'd recommend the McFarlane gaskets rather than halfassing it with some undocumented parts from Spruce.
https://www.mcfarlaneaviation.com/products/product/FC-KT-1/
However, it you do have the older flush-fitting "Killer Caps", here's the link to SK182-65:
https://support.cessna.com/custsupt/contacts/pubs/ourpdf.pdf?as_id=34886
If your fuel cap is the plastic version, I believe that you are out of luck. However, if your fuel cap is the metal version, they are just standard MS29513 O-rings which can be purchased from any vendor. I prefer O-Rings USA.
http://www.oringsusa.com/ The outer o-ring is MS29513-338, and the inner o-ring is MS29513-012. The little inner o-ring that goes around the shaft is actually more important than the outer one, when it deteriorates it's the one that funnels water into the tank and gives "Killer Caps" their name.
You could also consider installing the Monarch replacement cap kit, but I've never had water in my tanks using the alleged "Killer Caps" even after torrential rain. There is no specified replacement interval on the o-rings, but I do mine every other year.
http://www.monarchcaps.com/