Not sure if you have the rear patio deck option, but if previous owner left it open during rainstorms and didn't silicone around all the edges (and sometimes even if they did), water leaks in around the edding causing rot.
2015 Black F-350 Platinum Diesel Dually Crew Cab
2019 Riverstone Legacy 38MB (Full Paint/All Options)
2015 Voltage 3990 (Full Paint, All Options) Sold 6/18
2005 Harley Ultra Classic w/too many miles