For clarity about coupe and sedan / saloon and wagon propshafts:-

The coupes have a shorter wheelbase so their propshafts are of a different length.

Within a specific W123 type - such as a 240D - the rear section of the two piece propshaft is often the same length but a shorter or longer front sections were used to mate up to 4 speed manual transmissions or the 5 speed manual which is a longer gearbox or an automatic transmission. Swapping short pieces about is possible if you are doing a conversion though you might come a cropper with the absence of factory alignment marks...

Some information about the colour codes can be found here =>

Gearbox comparison & drive shaft lenghts & colour codes - Mercedes-Benz Forum

Please note:- "Not all yokes are equal"!

Some propshafts have larger PCDs at the yokes than others - different sized flex discs too!

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!