The timing of this thread is interesting. I spent an hour or so yesterday messing with my garage door opener and header height so that I could park the new to me F-450 in the garage and out of the sun. I have one of those Chamberlain Quiet belt drive garage door opener models that I installed about 10 years ago.
It's easy to set the open and closed positions, so after getting the door to open such that the bottom of the door was above the header, I simply removed a 2x10 that I had installed when I had the garage door replaced and now I'm able to get the truck in (minus the antenna). Ford says that the truck is 82.1" tall but I have about 1-1/2" of clearance between the top of the plastic markers and the underside of the header which isn't 82" from the ground. A salesman told me that those plastic "blobs" are to indicate the safe height if you're loading stuff over the cab, on a ladder rack I'd assume, but who knows if that's their actual purpose.
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