I'm pretty sure the '70 b-body AM 8-track was a max total of 4 speakers (three in the dash & one in the package tray)

but this leads to questions, FADER makes sense Front VS. Rear …..
work how does the BALANCE work with 3 speakers in the dash? is it set up Center VS. Outboards?
& what channel is the rear speaker on? same as Center?

paging "BigMoneyLewis", your assistance is required