Fuel filters, oil changes, coolant flushes and the om606s with live forever. My 98 had meticulous oil changes every 5k on synthetic and the timing chain wasn't replaced until 315k miles. That was the original chain from what records say.

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k

I just passed on the one i was most likely to buy, a rust free late 98 5 speed manual 3500 extended cab dually that had to be from somewhere down south. Not an ohio truck, i know that for sure because you couldn't see through the lower half of the body. It sat uptown for sale forever and just disappeared a few days ago. All of the chatter on the diesel Cummins sites about 53 blocks and the electronics on the 24 versus the 12 put me off of it. the dash top looked like someone had taken an ice pick to it, something else that seems common to the 94 on. if i see another one, i'll let you know. glad that the mb's seem a bit more consistent in model runs than dodge trucks and Vw's.
(side note, i can actually use capital letters and the space bar like an adult but my third laptop keyboard is going south intermittently and i'm waiting on a replacement laptop).