I do have a 3.0L that I plan to use in my 190E unless I find a good M104 3.2 or 3.6 locally. It's untested but I bought it from a Mercedes indy's parts yard. He said it had a head job done on it by one of his Mercedes indy buddies, no clue what that entails. ~210k miles. I would think you can probably find something closer though.

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Current: 1975 450SEL, 83 300D, 88 Yugo GVX, 90 300D OM603 swap, 91 F150 4.6 4v swap, 93 190E Sportline LE 3.0L M104 swap, 93 190E Sportline LE Megasquirt, 03 Sprinter, 06 E500 4Matic wagon.