Seems like a 2008 would have a 30 amp power cord especially if the A/C was installed at the dealer or the factory. Have you looked in all the compartments to make sure it isn't stuff in somewhere? Sorry, not much help.
2016 Ford F150 Platinum
2013 Coachmen Freedom Express 233RBS
Prior: Jayco Pop Up, Shasta Bunkhouse, Rockwood 2560G Pop Up