Original 5 cylinder diesel engine was scraped. What the best engine to replace the original? Can I move up to a recent year Turbo Diesel?

Replace with the same that came out of it. The oil filter mounting is different on the newer ones 82-85 and new then that just won't work. Try metrics, GAP in atlanta, Parts south in atlanta, or NOELS in FLA.
Good luck,
turbo herb

Another good source for rebuilt engines would be Metric Motors in Canoga Park, CA. Prices for your engine are as follows:

300D 617.912 Shortblock $2,600
Longblock $5,100

Shortblocks include: 12 month unlimited mileage parts and labor warranty (all OE parts).

NEW:
pistons, oil pump, rod and main bearings, timing chain, chain guides, rod bushings, crank seals and spacers, freeze plug seals, oil pump drive and gear bushing.

REPLACE AS NEEDED OR NEW:
timing gears, flywheel ring gear, misc. studs and hardware contained in block.

MACHINED TO EXACT FACTORY SPECS:
bore and hone, surfacing, align hone, connecting rods reconditioned, reground crank, balanced crank assembly.

LONGBOCKS INCLUDE:
everything covered in shortblock as well as pressure test, resurface, new valve guides and reground seats, new valves, new rockers, new ball stud adj. - hydraulic lifters, new chain tensioner, complete gasket set.

DIESELS ALSO INCLUDE:
rebuilt and calibrated injection pump, new injector nozzles, new prechambers, new rocker arm shafts, new glow plugs.

Well, there ya have it. If the body is in real nice shape, I'd go with the rebuilt longblock, and have another 500K to look forward to!

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Rgds,
Aaron Greenberg
MB technician
'67 250SE Cabriolet
'77 450SL
'79 6.9
'79 6.9
'80 300SD
'81 240D
'85 380SE
'89 420SEL
'93 300E 2.8