[Mr70]

You're right.RPO U79 was not a Factory option for the 1970 Camaro.It was in the Chevelle & others.It has a more symphonic sound,and should use 4 speakers when installed,for optimum listening.
Could you get 2 front speakers,and 2 rear speakers in a 1970 Camaro?
The Mono used one speaker.
The Stereo is usually 100.00 more then the Mono,whatever condition it is in.I don't have one here now,but I will look for you at Jefferson this weekend if you like.