I think you’ll find this is a generic part not a Winnebago part. A search for “rv roof a/c gasket” will point you to hundreds of options. Amazon has hundreds of listings for the part.
Assuming you have Coleman-Mach A/Cs here’s the part number for the OEM part
Coleman 83323301 Gasket Kit
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2017 Winnebago Adventurer 37F
2016 Lincoln MKX Toad
I had all three replaced a couple of years ago at an RV Repair Place.Seems most RV Repair/Parts places will have them.
You will need the model of AC.
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Wayne MSGT USMC (Ret) & Earlene (CinCHouse)
2015 Winnebago Tour 42QD - 2020 Lincoln Nautilus Reserve (TOAD)
(RVM-14) It is what it is, and then it is what you make of it.