Seems like a pretty good deal...the sticker price on my parents '71 New Yorker was $6,600..... no clue what they actually gave for it, but it could'nt have too far off.
Off the subject a bit.... I def remember a local ford dealer offering F150 shorties with a Meyer plow at a special price of $5,500 brand new in '77.... that's not a real solid combo since the trucks were'nt really HD enough for plow duty.... but for only 5500, I'd have a new one every year if that pipe dream ever returned lol.