This is how I repaired mine.
The skin was corroded almost through and the rivets had pulled through. The pan was very loose.
1. I located the center of the frame rib (steel) all the way across the bottom.
2. Took a chalk line and pooped a line across the bottom.
3. Took a small piece of the aluminum strip and made a guage (made a center line down the middle of it. Held the center line on the belly skin and with a pencil marked the front and rear of the strip with a pencil.
4. Layed out and drilled the holes in the patch strip.
5. Had a friend help hold and align the strip between the pencil marks on the belly pan on each side of the rib.
6. Drilled the first holes (into the rib) in the middle and worked out from the middle. This will prevent bunching or puckering that will occur if you start at one side and work all the way from one side to the other. A very sharp 1/8 inch bit is necessary.
worked out from the middle until finished.
See picturers at
I did not seal the rivets or the patch because if any water gets on top of the belly pan you want it to seep out. However if the steel rib is showing, place electricians tape on rib to prevent the aluminum patch strip from touching the steel. The reason the aluminum corroded into at the ribs in the first place was due to dissimiliar metal corrosion. The tape prevents the aluminum from touching the steel rib.
I have local supply of the large headed (aluminum pop) rivets here in Norfolk if you are interested.