yes it sure is electrical wiring your see.

 

Yes, it does look like wiring now. I got a look inside the door jamb today and it looks ok in there. In all the years I've owned my 300, I have never had the fenders or even the liners off. I could probably just pull those and see everything that might be trying to rust.

 

I haven’t looked closely at the T-bar roof set up of a 280ZX. z31s have two T-top water drainage holes per side, one in the front and one in the rear. It’s not exactly the best plumbing connection. A plastic tube is attached to the drainage spout with a putty. If the tube should separate from the spout, then water damage can occur. This FAQ covers it:

http://www.zeeyalater.net/comprob1.htm#wetseats

 

only problems a 240z has with the cowl is the open space leading to the bottom of the front fender quarters. leaves and stuff tend to wind up there. all cars had that back then. unfortunately, the 240z was more prone to rust, partially due to it's thin gauge sheet metal. i'd guess most of it is 22 guage with no backside protection. i rebuilt my 240 with 20 in the exterior sheetmetal and 18 in the floors.

you don't have a rust problem. your car looks pretty good for a near classic. i'd wire brush it, primer/undercoat and put it back together.

btw, sharp looking car! what happened to the mirror? that isn't the real reason you took your fender off is it? ;-)