If the 1989 is a US model then its a OM602 5 cylinder naturally aspirated diesel.

84 and 85 were 4 cylinder OM601

So if you get the parts cars they won't have the same engines as your "good" car.

OM601 and 602 are great engines

84 and 85 were available with a manual transmission in the us but a 722.4 automatic is not a bad gearbox either

winshield wiper mechanism on 1984 is just a single wiper with no articulation.

1985 and newer have the articulating wiper