https://www.dropbox.com/sh/c3dznkeu0g438fr/AADSuyHs4cSEQsAlCRqYQ4-La?dl=0

Here is an odd ball for you.  I believe it to be a 1974 head case and chassis, with a slightly older 2203 circuit thrown in.  But I don't know enough about PCB and component differences to date the insides.  I do know that I haven't heard of a 1974 2203, since they came out in '75.  It has two inputs, but says Super Lead on the back.  What is it?