The 100 Bilinear is circa mid-70's, sold under various names such as Bimbo and Hooker. The PEP/RMS switch is nothing more than a HI/LO switch. I have one with a pr. of PT7984's in it, switchable between 60 and 90 watts (IIRC) with a stock CB driving it. First amp I ever bought, the only thing I ever had to do to it was replace a relay, and believe me the thing has taken a beating over these many years.