I "think" the back doors would be different, since the 500 is a "long bodied" (L designation) w126. In addition, your 300SD would have the vacuum cut off part attached to the ignition and the 500SEL would not.

Vacuum pods, light switches, seat parts, carpet (with the exception back seat floor pieces) should be the same. ACC may NOT be the same --- I don't know.

Things like power steering pump, alternator, etc might be the same. If I had to guess, the starter is probably not the same.


edit: Brian can type faster than me and is not a long winded, "Southern" gentleman.

__________________
daw_two
Germantown, TN

Links:
Sold last car --- 05/2012 1984 300D Light Ivory, Red interior
No longer selling Cluster Needles Paint
No longer selling New Old Stock (NOS) parts

Past:
3/2008 1986 300SDL "Coda"
04/2010 1965 190D(c) "Ben"
& many more