Hi guys...
Have a 300sdl(w126) with bad rod bender, also have a good 603 out of a 2000 300d (w124).
Besides the oil pan and engine mounts, anything else needed to swap...Are the trans the same? The 300d trans is known to be good , so would rather use that one.
Any insight would be greatly appreciated.

The 300D trans will have the right shift points for the 3L engine, but it won't have the right hook up for the W126s electronic speedometer.

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

are the plugs/parts easily swapped?

I believe the entire tail end of the transmission is different. The W124 has a cable speedo.

-J

Thread subject says 350SDL. Here it says 300SDL. The 3.5 is the rod bender.

The W124 didn't make it to MY 2000.

Make sure the oil cooler line fittings in the oil filter housing line up. If not, swap housings. Doesn't matter which oil filter lid you use in an SDL.

The 300D turbo compressor air inlet snout might be longer than the 3.5's so you might have to modify the 3.5 air inlet hose if the 300D hose doesn't fit. Ignore the ARV in the 300D turbo. You can leave the ARV vacuum nipple disconnected.

Save the 3.5 head. It'll likely be a later casting you can use if the 300D engine overheats. Save the cam, cam towers, injectors and injector lines with the head.

Reconfiguring the tranny is more work than it's worth, IMO. Don't swap or swap and use mach4's external speedo drive mod.

Sixto
87 300D