To the OP:
knowing exactly what model you have is critical, as stated.
I have no idea if the 77/78 "K" model side covers will "fit" an "F" model but regardless they are not the same shape. In my opinion, if an external part isn't the same shape, I probably don't want to spend the money for a part that doesn't look right. The pic shows '78 "K" model. see the curved front? So in my opinion, frankenstuff is wrong.
CMS is a good source for interchangeability. However, in this case, since the OEM part came as a specific color, this function doesn't work quite well. For example, a '76 "F" model side cover I know for a fact fits on a '75 "F" model. But CMS only shows it "fits" on '76 models, any country, only...because that color was only for '76 "F's".
point is, do your due diligence when trying to source correct parts....beware the internet.