The F150 extender I have doesn't seem any longer than the ST extender, but the uprights need to be moved a little bit to line up with the indentations in the tailgate they're supposed to rest in. I didn't have the factory cover when I used it, but I do now. I'll have to check if it flips without interference. On one hand it seems logical that the F150 extender is longer, but some years/models use the same tailgate as the ST. I suppose the mounting points could be different though.