as the title says, would any w203 body components fit a w209?
Rein bar for example or fenders bumper etc?

Nope, none of the body parts fit. The hood and fenders are longer on the W209 and the bumper has different detail around the headlights and grille.

Well. I heard c55 front bumper is the same. I'm sure some interior would be interchangeable as well. But as for body components, most likely not as rudeney has stated

Yep! The C55 uses the CLK wider front & nose. No standard W203 body parts fit a W209.

C55

I know the C55 front end is different than the standard W203. It makes it 3.4 inches longer to accommodate the V8. It looks similar to the W209's, and looking at EPC, I do see that several parts like fender shrouds are shared, but the body panels (hood, fenders, bumper) and headlights are unique part numbers. That doesn't mean they won;t fit, it just means they are somehow different.

They will fit but there are minor differences one needs to look out for, wide Grill etc. is interchangeable. Hood is the same & will fit but e.g. it is punched for the hood ornament (sprung star) ~ whereas the W209 is punched for flat badge. Side impact strip where fender meets door is different. So they are interchangeable with work arounds. If one does not want any work arounds then don't use C55 parts.

Here is a W209 with a C55 wide grill as an example. The front of a W203 is narrower. W209 & C55 have wider & longer nose.

Hello friends !
Looking to see if a 2004 e500 4 matic
body parts (fenders, bumpers and doors) would fit on a 2001 E430 4 matic