Extremely Rare Concert T-Shirt Day on the Green The Who and The Grateful Dead

Description

This is an extremely rare t-shirt for The Day on the Green concerts on October 9 & 10, 1976 at the Oakland Stadium in Oakland, California. The concerts featured The Who and The Grateful Dead. This was the last time the original Who lineup played the Bay area.
The front of the shirt is screen printed with the image of a Native American chief with "The Who" printed on his headdress. The festival name is printed below. The back of the shirt features the iconic skull and roses logo for The Grateful Dead with the festival name again printed below. You could also buy this shirt design reversed, with The Dead on the front and The Who on the back. The color has faded from navy blue to a mellow purple.
The label is completely worn away so I do not know the t-shirt manufacturer or the fabric content. It is definitely cotton, but I do not know if it's 100% or a blend. As for the size, the shirt is pretty small which is why I have called it an XS. Please note the dimensions taken flat, one side only:
Shoulder to shoulder:  13 inches
Underarm to underarm: 15 inches
Length: 23 1/2 inches
This shirt is in nice condition considering its 40+ years. There is one tiny pinhole on the front (see photo #10.) There are some pinkish spots - loss of color? (see photos 11 and 12) and a small spot with a loss of screen print on a leaf of the Dead logo (can be seen in  photo #5.) The Grateful Dead logo has a little bit of cracking. The Who logo has almost none. The screen printing actually still has some shine to it, which is remarkable.