So I removed the back half of the wiring harness I peered into the area between the firewalls some. What I saw seemed to make me think if I do not cut access holes in the back firewall to fix what is starting, I may be putting a lot more work into this car in the future................

Pics:

Can't see any pics but if you are talking about the double-walled lower portion of the firewall, it's MUCH easier to access if you simply remove the rear bottom part of the floor pan.

This will give you access to the *complete* double walled section and it's very easy to work in there that way, plus, you can close it all up easily by simply spot welding the floor-pan piece back on.

IMHO, much easier than any "access hole" can ever be ...

Wow. That's nasty. I'd tear it out just to make sure.

I suck and did not paste the imageshack link then lost it. I will take another pic and post it after work when I am back home.

Do I just sort of cut it where it meets the inner rear firewall that is in the cabin, and then spot it back up on both ends?

Sort of. You should be able to drill out the spot welds on either side of the firewall and then cut the floor pan in a way that allows you to spot weld the floor piece back on later instead of having to do a butt-weld.

I'm at work and don't have any pics right now ...