This eBay listing caught my eye, purporting to be a Lambeau Field grounds crew jacket from the 1970s:
The jacket itself is fairly unremarkable, a simple green nylon shell with sheepskin lining.
The jacket features a single-bar gray facemasked helmet graphic common to the period. What's uncommon, and what caught my eye, is the logo on the helmet: the green and white are reversed.
Ordinarily, this might be considered the mark of bootleg merchandise, except that the Packers themselves used a reverse-colored logo on occasion. The earliest example I can think of was in 1962, when the watch given out in lieu of a championship ring featured a reversed logo.
That was only one year after the logo itself was introduced. More recently, the 1997 stock certificates also featured this green-on-white logo.
For a while, the reversed logo was even seen on the side of Lambeau Field, such as this glimpse from the 1980s:
So it's certainly possible that this is an authentic grounds crew jacket. Is it worth $559.99 plus shipping? That is entirely up to you.