I did some of my own research and found a great Forum at Pyramid Air. The rifle is a 'Diana' 35, marketed under various brands including Winchester. Diana production ended in 1987. I think mine is a mid-70 product. Considered high powered 35 years ago it was out performed by the later long piston units. I thought the rear optical sight was complex, the trgger assembly is incredible. It is a ball-bearing device that looks like it came from a pre-war machinegun. They called it an 'adult' airgun, you have to be to even pick it up. I saw an estimate of the value at $1000 for a so-so rifle, $2000 for a nice one. I also saw an nice one [?] offered for $400. I wouldn't pay $2000 for one of these NIB autographed by Paul Mauser. I don't shoot this much, I do display it.