Since the fins were bondo'd to the car,
water and dirt accumulated on the top 
of the rear quarter panel.

The trick here was to cut away as much of the damged area as possible.  But that presented a problem; it's in this area where Studebaker  welded the rear pieces together and "tinned" them.

At the tinned cut I welded in a new section. The trick was to mate all the compound curves so there would be a minimum of grinding. Plus I needed to fabricate a new flange or lip for the new quarter panel to mate.

This is the finished product. I used a piece of steel plate and a hammer to bend a four curved/angle piece of sheet metal to meet the new inner rear fender. 

This is the Classic Enterprises trunk repair panel for the trunk corners. Most people think that the water that enters the trunk comes from the bad seal of the trunk lid not meeting the rubber. I dscovered that the water that enters the trunk is from the rear passenger side windows. Water drips down from the window area, then air rushing by, shoots the water along the inside of the rear wheel well on the inside, then the water 'pools' in the corners.

Everyone looks for rust damge on Studebakers around the front fenders vent area and the top of the front fenders.  This is where you will find hidden damage that can ruin your car. This is the Inner body area where the rear passenger window rests when the window is lowered.

The only way to remove the rear quarter  is to remove the rear passenger window. There are two fasteners insie this area that can only be removed or replaced witht he window mechanism out.

Be sure to retain the Special Pivot Screw located down inside this panel. Tat screw allows the window to pivot to the rear, and then foward as it lowers.

This is the result of mating in a new upper body panel, welding in a piece of sheet metal that became the new trunk side wall, and the inner body panel. You do not have to replicate the indents in the sheet metal, as nobody will ever see it.

Once this repair is made, paint the area, and once dry, apply a thick coat of undercoat. The undercoat should be thicker foward, and to the rear of the rear wheel. Dirt and moisture really accumulate there.