From your picture, that oring looks more like the supplied DIN oring which you do not need. That's an extra in your kit. See if there's another that matches your original.
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I am having a rough time finding a 2x11 EPDM Duro 90 anywhere. Can anyone help me out?Either Viton or EPDM in 90 durometer
Official service kits use EPDM. Viton is better for O2 applications.
I did try McMaster Carr after reading your post but they didn’t have what I needed earlier. I ended up buying a kit from a different retailer. I hated to do this but I will have a kit for it for next year that way minus this oring. I may be able to reuse this oring next year being it’s a static oring but I will just have to wait and see. Needless to say I am not exactly thrilled with the place I purchased the original kit. I kind of get impression that they don’t care their kit was wrong.Going to be difficult to find just one except from an LDS or another DIY'er
https://www.amazon.com/dp/B005RUQT3A/ref=biss_dp_t_buying_options
Edit: just noticed it says out of stock.
Have you tried McMaster Carr ?