A question about the AM FM radio

[Leon in Mn.]

Hey guys I have a question about my old AM FM Delco radio in my 67.  Right now there are two rear speakers mounted in there (someone mounted Kraco's back in the day) and one speaker in the front.  The front speaker must not be hooked up because its not working.  I'm assuming that this was a mono set up at one time?  There are no kick panel speakers.  The front speaker is there, but from what I can see it is not hooked up.  I cannot seem to find anywhere that there was supposed to be just one speaker in the rear or should there be two?  There are two cutouts for the speakers (trunk view)which appear original.  Since this would not be stereo sound, would they have still hooked up the one speaker in front along with the two rear?  Thank you for your help.

[My68SS]

Bit tricky navigating my way through the RPO list and AIM on this topic, but it seems the standard setup for am or am/fm [mono] in 67's was a single speaker at the front as per U63 in the AIM.
An aux rear speaker RPO U80 could be ordered, which was fitted to the RH rear speaker cut-out.
The stereo 4 speaker system was only available with the stereo tape player.

How the speakers were switched between the tape player and the radio and wether all 4 speakers were driven by the radio, I'm not sure.
Maybe the radio defaulted back to the single front speaker and only the tape system drove the 2 kick panel and 2 rear speakers.

What happened in 68 when am/fm 4 speaker stereo became available, is another minefield I'm yet to navigate! 

btw, rear antenna was only available for am radio only, not am/fm [too much signal loss over a long antenna lead]

[Leon in Mn.]

Thanks Rob, that's what I have been trying to find out.  If it was supposed to have one or two rear speakers, and which side.  I would be just fine to hook up one rear speaker and a front one like it maybe should have been.  I have found that the rear speaker(s) were grounded behind the rear seat somewhere with one wire going to the radio.  Looking up under the dash, it looks like someone did their own version of wiring.  I may have to pull the radio and find out which color coded wire goes to which speaker.  I'm sure the radio should be grounded as well.  As for now, I will have to make some sense of this.    Does anyone where I can find the shelf speaker covers?  I don't like the ones that are in there now.  Thank you for your help!