The Fisher 100-R Tuner and MPX -100 adapter ??????

The 100-r tuner has a & b channels but are they both in mono? I have a MPX -100 adapter that is marked L & R . Can anyone explain how to hook this up properly and what are the two unparked pots on the back of the mpx ? the front ones are marked level . and What in the world is the FM-AM setting on the tuner . It seem fm comes out of the left channel and am comes out of the right channel ? BTW this is a good sounding tuner with a cat eye scope type indicator that can be bought pretty cheap on the web! Thanks !
In the dawn of stereo broadcasting, before multiplexing, and for a short time only, somewhere around 1961, the right channel signal was broadcast on the AM dial and the left channel signal on the FM dial. Tuners of this era hence needed seperate tuning capacitors for each band and are of little use today unless they have a multiplex output which can be fed into an outboard multiplex unit such as yours.