Ok.I answered my own question...The AM-FM multiplexor in use with the 8-trk # 7305221 did not have any knobs.It took the place of the std convector (heat sink) mounted behind the dash.So ...it would not mount under the glove box but behind the dash out of site.And yes,the knobs on the 8-trk control the multiplex function......Sorry...It's been awhile since I studied this P.I.T A set up..
Steve