My understanding is that all w124 from 1986 to 1993 are a bolt on swap (seats, door panels, etc).
This is not a definite answer, but maybe someone will shed some light.
May I ask what colors are you replacing and getting?
I am interested in some interior parts myself (gray).
1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car