<<I had to fabricate a new front pan for our SDL, the original was long-gone. I made it out of roof flashing, fiberglass, and fiberglass batting (insulation). It's a thoroughgoing mess now, due to the 603's penchant for oil leaks, but it did quiet the outside of the car down.>>
The pans noticeably quiet the car down inside by eliminating engine noise reflecting off the pavement. I would guess that a pre-CDI MB diesel could not pass Switzerland's pass-by noise test (just one country with this requirement, there are others) without a pan. The 1989 Porsche 911 model 964 has an enclosed engine because of the Swiss law. RLE