LEB Ben
Arrogant A-hole At-Large
Maybe its a late 77 and they just switched the grille out?
Just went back and looked at it a little more in depth...it's definitely a late '77 for all the reasons Eric said...and a quick look at the VIN (assuming it's correct) shows it is in in fact a later '77 because it's after Y20,000.
For the record...the grille remained the same throughout '77, so no swap is necessary.