Well, had the carpet out and drove it in the rain yesterday. Had some water back there and it looked like it was coming off the top of the wheel tub. Yanked off the trim expecting to find water running down from the side or alpine window.
Nope, coming from a hole located on the top side of the wheel well. 3/4" diameter.
H'ware store didn't have a rubber hole plug so I grabbed a pipe/drain/well plug of sorts.
The other wheel well has some tarry looking square patch thing going on.

 

At least it was simple........ this time. The "C" pillar is where it all begins, it's the Achilles Heel of a D1. It's the main reason why there are so few Northern/Eastern D1's left. I had somewhat of an idea of what that area looked like but the tar patch and steel was long gone on both sides of mine and it ate through the frame to body mount. If you plan on keeping it you'll want to fix the surface rot cuz it's only gonna get worse and that's a tough spot to fix.

 

Think I'm going to keep it a while.
Truck has spent most of its life in the S.E. except when po worked in Alexandria, VA for while.
Did find a hole due to rot where wheel well and floor meet.

I've seen worse, grew up in Detroit.