Looking for a Zenith Service Manual - Anybody? Bueller? ... Bueller?

[ZenithDude]

I finally figured it out. They didn't go by model number after System III. I was "digging in the wrong place." You were right about "Chassis Numbers" vs. manual reference being obsoleted since it was all modular through that run with revs to the boards. I just needed to pickup an "M Series" Zenith Service Manual - (M for "Modular") and make sure it was dated either late 1981 or 1982. My set is August 1981. I found a 1982 version. I ALSO found a binder from an old Zenith Service tech that holds every Zenith service bulletin from 1968 through 1982 - and which should help me in case I run into any compatibility or tricky calibration issues after repair, replacements and refurbishment. I'm hoping these last 2 pieces of the puzzle lend a solid education on System III.