I did some searching and it appears its only available right now for OEM installation. I did find several folks selling new/removed suburban grills. Have you looked at the blackstone griddle?
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Retired Navy
Jake my sidekick (yellow Lab) 10/04 - 05/20
2017 RAM 2500 CC 4X4 Cummins Diesel
2016 Flagstaff 26 FKWS
AF&AM & El Korah Shrine of Idaho
From the pics I've seen, the Suburban griddle looks like it was made by Blackstone. It looks exactly like the Blackstone 17, just different logos. I'm guessing Blackstone makes it for Suburban.
Saw the Suburban grill at the RV show. It’s about half as deep as the Blackstone 17”. On Amazon you can get a lid for the Blackstone which helps with spatter and keeping the heat in. Love our Blackstone, we have never used the original bbq.