Here is what I found:
nice 1” crack length wise facing the drivers foot in the 8” hose to the heater core, surrounded with brown evidence of old coolant … just as @panterapatt laid out from a previous experience of his!!!
rusted heater control cables, interesting wiring.. twist and tape, a GM plastic piece that just fell out - landed in garbage can eight seconds later… and lots of dust and dirt… Removing the heater control panels with the cables is a B@&$!!!!!!
lots of old gooop over all the connectors for the A/C , hard and non-cooperative…
i’m glad I’m very easy tempered! Otherwise, the chainsaw would have come out! 😡🤬🤯