Just wanted to give those that might be curious, an idea on part of what my project has been lately that has taken up much of my time as of late. These photos show 13 different 2600s that I recently serviced and installed UAVs into along with all the needed AV jacks installed as required by the client.
An no...these do NOT have two sets of audio outputs. The red/white on the left rear next to the 4-pin s-video mini din, is actually separate chroma/luma connections. This is handy for connecting to older monitors that only had RCA jacks for s-video connections. The yellow & white/red on the right rear are the composite and dual mono audio outputs. I figured the easiest way to keep it separated given the RCA colors I can get, would have been to keep the s-video all one side and the rest to the other.
Most of these consoles are revision 13 with a few 12s, 14, and even one revision 16 in there. UAVs install pretty much in the same manner regardless of revision with the only difference being a few changes on where some of the video signals are tapped from due to changes in the PCB trace designs.
Last is a pic of 1 of a few 7800s that are also part of this project. The first 7800 is essentially done minus the av jacks and wiring for it. But this is essentially what a 'works' upgraded 7800 from the ITC looks like these days. It has new front panel switches, new capacitors, a new dc-dc switching regulator in place of the linear voltage regulator, a Kiloparsec BIOS upgrade, and a UAV installed on top of one of my mount boards I designed a few months back.