Installing a newly rebuilt heater/A/C box?

[Mheiron]

I’ve started a big dash rebuilding project and want to install a newly rebuilt instrument panel, radio, new wiring harness and the new heater box.
I’ve changed these once before but not on a 69 Charger.
My forum question, is it possible to get the heater box out without removing the dash? I’m thinking I can wiggle it out with the dash in place but thought I’d ask the forum if my clever plan would work or if a can of worms was waiting for me! I’d appreciate any words of wisdom. I’m hoping to have a working restored AC system, radio and instrument panel when I’m done.

Second question, I found a mystery plug that doesn’t show up on any wiring diagram and doesn’t have an obvious plug in point. Two tan wires, one red. Female 3-way plug. No idea.

Thanks in advance for any ideas or pointers

 

[andrewwoz]

I was able to get my non ac heater box out and back in with the dash in, removing the glove box helped a lot.

 

[gtx6970]

Yes.
Tight but doable

 

[pnora]

That 3 wire plug is for the safety relay for power windows.

 

[Bird 426]

My opinion, but this is why I prefer a FSM over the laminated wiring diagram. It's surprising where you find what you are looking for outside of the particular vehicle diagram that you are looking at. I have one laminated wiring diagram, that is why I I like the FSM better.