From the looks of the reservoir in the parts program, it looks like diesel owners might be getting screwed. It looks similar to the gas reservoir only it isn't available separately. I can tell you from replacing a bunch of them that the groaning noise from a plugged filter is simple to fix on the v6 and v8s with the disposable reservoir. Based on the look I'll guess that the diesel also has a filter in its reservoir, it just isn't replacable.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician