the manual & auto transmission engines are the same but they have a different flywheel and flywheel bolts. the engine crank and flywheels may or may not have balance marks.
a 1977 or newer 240/300d or any 300d turbo will fit but will require an adaper plate between the engine and transmission (found on all these post '76s) and relocation of the oil filter. newer engines are worth it just for the ease of changing the oil. w115's are the best.

don