Ron - Sure you measured,,, looks like the ht difference from the top of the AC cover is at the most 3inches, looks more like 2,, wish I would have measured when I was on top.
My a/c unit is currently my highest point and it clears my garage door opening by just 1.5" when the rig is empty and low on fuel.
I didn't want to remove anything like a Max vent cover to get the rig in the garage because as I get older I forget more and more.....maybe I have too much stuff stored upstairs.
