I keep thinking about injectors, just because mine have 260K on them and have never been out(just like the glow plugs).
But every, single diesel tech of any age and/or experience has told me if there not smokeing or tapping or doing anything really really bad, leave them the heck alone. I generaly don't listen to good advice, but I might this time around...

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One more Radar Lover gone...
1982 VW Caddy diesel 406K 1.9L AAZ
1994 E320 195K