jim, take a close look at figure 4R, in the stuff I sent you,both mono and stereo radios both only have one heat sink for the RADIO alone , the MULTIPLEX ASSEMBLY which kinda looks like a radio heat sink for the stereo radio, its  job is to produce an amplified stereo sound, because the unit also gets warm like the radio it also has a radiator intergraded into it to remove heat from the multiplex assembly, thus there are not "two heat sinks" for the STEREO RADIO, the MULITPLEX ASSEMBLY is not a RADIO heat sink, Iam not real big on Delco radios but my guess is that the mono and stereo RADIOS are the same, the way you get stereo sound  for  the stereo option is the addition of the multiplex assembly . anips2009-03-24 18:51:00

When I replaced the radio I my '72, I started by removing the console between the seats and made my way forward removing more parts. The WHOLE center console was removed and a "U" shaped bracket that attaches the lower/center dash to the floor. From there you remove the radio knobs and support bracket on the rear of the radio. As for the speakers, to get within the 8-10 ohm range, you can and should wire the two 4 ohm speakers in series to give you the 8 ohms. If you wired them in parralel, you'd end up with about 2 ohms.