Skids, protect the diesel bits.
Crawled under my buddies last weekend to finally put a lift on and they have definitely saved him from hitting the filters multiple times. If you loose fuel pressure you are dead on the trail.
I remember watching a series of videos from Banks Power where they looked at aftermarket covers, they found that some of them alter the oil that gets sent to the pinion bearings and can actually cause premature wear. Was at least interesting to see how things work behind the cover.