u may run into engine mount issues, as w 126 body has turbo diesel from fact.

when u pull out the engines u can measure the difference in where it will sit.
i was told by a guy who does these conversion, u need the torque converter from the diesel as its stronger than the gas 380, mind u the 380 has even more hp than the diesel.

the rear end can be fun part, as 380 is a higher rev engine, not sure what u need to do, u may not have a lot of top end/ speed.

i have a w126 280se sitting here and wanted to drop a dsl in it too, but just too much work.

i have bought a 85 500sel several yrs ago that has a reg 300d in it.
i think it has a diesel trans with it, so i didnt have any speedo and oil pressure.

the car was very slow, as it has not turbo, 80ish HP, and a 500 has 230+ hp, that was a euro version so it got more oomph.

so good luck , God bless is all I can say.

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