240D engine parts: manual vs. automatic

[george d]

I hope this is not too dumb of a question!

I was just looking at an online parts catalog, and noticed that some very basic engine parts, like pistons, piston rings, main bearings, etc., are different for a 240D with manual transmission and a 240D with an automatic transmission.

I do not understand why these parts would be different. Did they use an entirely different engine in the 240D with a manual transmission? If so, I wonder why, and what other differences there are, besides the transmission of course?

Thanks for any enlightenment you guys can send my way!

George