Berkshire 100 identification

[nicwil]

I picked up (a few years ago) a Penton Berkshire 100 with the name Stevan on the gas tank and 57 on he side cover.  Wondering if anyone would recognize it?  I think it is a 1971 but not sure.

[Dwight Rudder]

Easy to find out what year model that this bike is.  What is the serial number off the frame ?   Is it a Steel Tank or a CMF frame with fiberglass tank ?
Dwight

Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.