Interesting, I own two M104 engines (94 and 95) plus a M102 (2000) and know others with both late and early coils.

Personally, I've not noted any higher failure rate on my early cars (94, 95) than what I've observed over my admittedly limited sampling.

Since the coils are interchangable, I'm going to keep this in mind whenever I come across any in the yards for spares.....

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles