Wow, that is one clean engine compartment. I did have a little rust around the front jack holes and under the right tailight. I bead blasted the rust at the jack holes and painted it with Por 15. I blasted the spot at the tailight and had to weld in some small pieces of 20 ga sheet metal. Then self etching primer, filler and paint. Can't tell it was repaired.
After 23 year most of the underside of the car had a thin coat of oil or fuel on it. I did not wipe any of it off. I figured anything to keep the salt out.

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1987 300D 146K Original #14 Head
One eye on the road, the other on the temp. gauge

Gone But Not Forgotten
1983 380 SEL Long gone
1983 300SD Wish I hadn't traded it in on a 90' Corvette
1989 300SE My all time favorite
1995 E420 Went like a bullet