I'm replacing the engine in my 1981 300 TDT. I've been looking for months.

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1981 300TD Wagon

I have access to a 1982 300sd that runs well, but has some issues.
Car is intact and driveable, located 50 miles north of Boston.

approx 190,00 miles.

owner not interested in restoring it, just wants to sell as is or parts.

this could suit your situation - drive it home, take what you want and scrap the rest

You must find another true "TD" engine = wagon, with the extra SLS pump as part of the engine block.
Sedans and other models will not work unless you plan to do the major modification to rear suspension and take out all Self-Leveling-Suspension hardware

The donor wagon engine I had sold pretty quick with an immediate deposit.
Good luck! Look for a complete donor wagon for cheap, likely too rusted out or bad transmission, but still running. The engine swap won't be too bad and a car full of specific wagon spare parts is worth it.

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1990 300D 2.5Turbo, two tank WVO, daily driver 300,911
1992 E300 gaser, 150k. Parts only, For Sale

[B]1984 300TD Euro 4speed Sold
1977 300D Elsbett SVO single tank Sold
1981 300TD "Silver bullet" 285k ran B100 Sold
1981-5 300D x 5 cars stripped and reused, parts for sale

Other toys:
1995 Dodge 2500 Cummins 12V P7100 Bosch mechanical pump with 2 tank veggieconversion kit, only 120k!
1959 Cadillac Dad's legacy, needs finishing

My source also has an engine which is out of the car and a head from a wagon engine with the sls pump.