Will the engine from my wrecked 420SEL swap into my parent's 380SL? Are there any differences between the two besides electronics and displacement?

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1984 380SL-driving and service privileges.

I'm speaking from ignorance, but I believe that you can make it fit, but will need to modify things a bit. The easiest engine swap is a Euro 500 engine into your 380 - that's just swap the oil pans and bolt on deal. With the 420sel engine I'm pretty sure you'd need to do something with the exhaust manifold at minimum in addition to the wiring harness issues you mentioned - not sure what else. Hopefully someone with more experience will contrbute.

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Tjohn

82 300 SD
77 450 SL (gone)

You will need to swap intake manifold, exhaust manifolds, oil pan, ignition distributor, & many other items like the motor arm supports. But you will have about 40 more HP!

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MERCEDES Benz Master Guild Technician (6 TIMES)
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Retired Moderator

Mercedes did offer a R107 420SL in Europe, so it certainly is feasible.