Good luck! My '81 SD has the same problem, I'm just avoiding crawling underneath, because I know I'm going to spend the next week under there, once I start poking around!

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1981 300SD - Sunburn Gold, 200ish k.
1984 300D Turbo "The Green Lantern" - Mango Green (DD) - 183k with no more fingers to count on
1979 300SD "The Whale" - Black (Back-up mega-sled, soon to be for sale!) - 160k and no longer keeping track...
Confucius say: Man who run behind car get exhausted, man who run in front of car get tired.