It's the same body style The 420 has US DOT aero headlights which are worthless. Your 380 has better lighting. You can upgrade either car to European/e-code lighting. The 420 has later style wheels. Same wheels fit your 380. 420 has smooth side cladding vs your 380's ribbed cladding. It's a bit of work to locate and install smooth cladding but it can be done.

$1000 is a gamble for a car you cannot check or have inspected. Let's say it's quick and cheap to get the engine started. Only then can you check things like engine compression, oil consumption, cooling system integrity, transmission, climate control, steering and suspension integrity, etc. I see good running 420SELs for $2500. Maybe not in the color combo you like and maybe not with low mileage, but...

Sixto