Belly pan $$$
The belly pan on my '98 tdi slowly deteriorated over time, first the torx screws let go and I wired it on, then the half under the tranny got implanted into a suicidal porcupine. Then the half under the engine ripped off going through some snow about 4" deep. By the way, when the belly pan was still relatively new, a towtruck operator rammed the oil pan with his wheel lift bar, and dented/cracked the oil pan with only a slight scratch to the plastic belly pan.
The roads in Northern Alberta are often covered with snow, pit-run gravel, rain, ice lumps, and road-pizza critters of all sizes.
The last bits of the belly pan dropped off about 100k miles ago, and there have been no issues. I do notice more road crud in the engine bay, however it has not precipitated any failures. I'm sure those aluminum pulleys on the serpentine belt path are experiencing extra wear from the extra grit flying about, but the serp-belt hasn't been destroyed. I do have the serp-belt replaced every time the cam-belt is changed, so it doesn't really get a chance to get really worn out.
The dealership quoted a price of ~$400 for the stock plastic iterm. They still have it in stock.
Just my 2 cents...
Mathew Banack Round Hill Alberta Canada