Game Used Football Help

[sek122482]

Hoping someone on here can help me out with an item I just purchased at an estate sale. It was a sale of the estate of the Raiders former photographer. I bought this football which appears to be used and is signed by many Raiders players. I can for sure make out Ken Stabler, Dan Conners, George Blanda and there are several more. After doing some research I believe that it is from the 1970 season because of the Block Lettering. Does the fact that this type of football was only used for 1 year make it very rare or are they fairly easy to get? Also, does anyone know what the "QB" marking means? Any idea on value? I would appreciate any help someone can give me on this. Also got a game used helmet I will post once I get some pictures. Thanks!

Scott
sek122482@yahoo.com