'86 300sdl - 603 motor. Original #14 head & head gasket. Runs great.

Just replaced higher millage maintenance bolt on stuff i.e. water pump, vacuum pump, timing chain, alternator, belt tensioner assembly, radiator, driveshaft recondition, radiator, hoses, glow plugs, shocks, tie rod links, brakes, several sets of tires, rebuilt trans at 250k due to front seal leak, etc

....and religiously changed the oil / filter every 3,000 to 3,500 miles. Currently running synthetic oil which seems to have given the lifters a little more life (no more clacking).

I'm thinking of replacing the original injectors but it still gets good as new mileage. Also put cheap engine mounts in while back because that was all I could find at the time ....I'll be replacing them with oem soon.

None of the above (x driveshaft u-joint vibration & motor mount) failed on me...they just had 300,000 or so miles and it was time.

Thought it was getting a little tired around 375k and then I adjusted the ALDA...& she's back with more low end power than I had remembered...kinda if fun.

Some around town miles but primarily highway and often (3 times / month) for long runs between San Diego to San Fran, Arizona, and Nevada.

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1986 300SDL 440,xxx