You will have to swap the entire engine, the IP bolts up to the timing chain, just like a diesel, and the carb engines don't have the flange.

If you can get your hands on a D-Jet setup for the 250, you will only need the wiring, ECU, and head.

This particular change isn't for the faint of heart, I'd recommend looking for a FI car instead.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!