A know fault on the R107 is rust in the rocker panels.

I have found a 1988 Model 300SL that seems to be in good condition for corrosion. I have been looking for some time. Most are already rusted out.

If I buy it I want to make sure that it does not go downhill.

Anyone know how water gets into the rocker panels as it seems to be a sealed area.

Any good idea's as to how to protect them (Externally and/or Internally)

I was thinking of cutting a small number of small holes (About 1/2 inch diameter), on the inside (Footwell), and spraying with a corrosion inhibiting compound. Plug them up after.
Also Zibert all round on the outside.

What other areas do I need to consider.

Mike