I believe the US cars are either 260E or 300E. There was a 300E 2.8 in the early 90's.
the 2.6 L or 2.8 L engines are little smaller. I think there are less standard equipments on the 260E or 300E 2.8. If I remember right, even the transmission and differential are a bit smaller in the 260E or 300E 2.8.
Chances are you are not going to see a much lower price on the 260E or 300E 2.8. I suggest you look for a 300E and there are plenty of them around.