As said coupe, saloon and even estate doesn't make a difference but engine and sport chassis does. I thought it was just the 320 (and maybe the 300-24?) that had non-replaceable lower ball joints though as in 'compatible with' lists i've seen the 280 is included with the 4 pot petrols and all the diesels (as well as some w201 and r129 models)? Dunno whether the sport chassis thing is just bush hardness or if there's geometric changes too, i'm thinking just the former as model year appears to make a difference which'd kinda make sense as the sport chassis got softer/more refined on later cars?
There are I believe slight changes to the geometry of the arm [ the angle of the ball joint to the arm] This to accommodate the slightly lower suspension. Its why I believe there's is a sensible limit to how far you can lower the suspension by shortening the springs without placing undue restrictions on ball joint movement . There have been instances in the past where folks have mistakenly fitted standard and " sports" arms to different sides and ended up with a car with an uneven ride height side to side.
ps these fixed ball joint arms are used in the 320 6 cylinder 400/500 V8 and most Sportline suspension models afaik
That makes sense re ball joint travel. Makes things more confusing though for example... German SPOB: KOMBI Estate (S124) 320 TE (124.092) Track Control Arm 15694 10730026 1243303407 which is showing the equivilant MB part # to be A1243303407 and A1243303607 which as i understand it refer to the later standard wishbone and the late sport chassis version respectively, both LHS. From MB the latter is £105 more and a bargin @ £440
Another explanation ----" all cars over 200HP have the non-replaceable balljoints, cars below have replaceable ball joints. No matter what year.
The reason is, that the bigger (4-pot) brake/thicker ventilated disc needs more clearance - hence the LCA & balljoint needed changing. The LCAs with replaceable ball joints are not interchangeable.
The LCA however is the same for all cars above 200HP - 300E-24, 320E, E320, 400E, E420, 500E und E500."
AND
The jury is still out on any change in arm/balljoint angle - have yet to find out what the difference if any is.