From an eBay ad for an 8-Track AND a rear single driver's side (my A12 is this and 5"x7" not 6"x9" in size) speaker with fader wiring harness:

Original Mopar 4 Speaker stereo speaker wiring, filter/splitter box and front-rear fader for 1968-70 Dodge & Plymouth 'B' body cars. These special harnesses were used on cars that came from the factory with an AM/8 track stereo radio and a rear seat speaker; so it is actually a combination of two options: R22 AM/Stereo 8 track radio (with three speakers) and R31 single rear seat speaker. Contrary to what you may have heard or read, there was never a "5 speaker" option (with dual rear speakers) or an AM/FM stereo radio option for the 1968-70 B body cars; the AM/FM radio was mono only (R21) with just one speaker (two if R31 was ordered). This is the "maximum" stereo option speaker wiring harness for the B body of those years, and is actually made of four parts: 3 speaker dash wiring harness, special stereo front to rear fader control, splitter box for center speaker, and rear seat speaker wiring harness. Also included in this auction is the special clip that secures the wiring in the trunk. No cuts or modifications at all to these genuine original Chrysler parts, and they all work perfect; control has no static in it at all (I hooked it up and played music through it). This is a very rare harness/set-up. See my other auctions for more Mopar parts, I will combine shipping to save you money on multiple purchases.

See my other auctions for more Mopar parts!