The W124 chassis had both engines fitted. The W126 chassis had just the single cam fitted.

Given that the fuel and ignition systems have virtually nothing in common, you'd need both W124 cars side by side to make this project even remotely cost effective.

Since the W126 has none of this interchange available as a factory model, you're going into unexplored territory. I've made these one of a kind swaps before, and let me tell you, it ain't pretty.

This is something that needs the three T's: Time, Tools, and Talent.
If you don't have all three, don't even start this kind of project.

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