All three cars I've pulled the drivelines in were painted with YELLOW lines for alignment. The marks are underneath the undercoating on the driveshafts. You'll need some degreaser to remove the undercoat, then you should find your marks (either arrows or paint). This allies to the '82 240Diesel, '86 244 DL, and the '85 745 TI.
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JohnG 1989 245 MT @216,500

Nickvjr is right about the arrows. Clean the grime off of the shaft and you should see them. These pics are of a 50.8mm driveshaft from an '84 DL. My earlier '79 & '80 cars with the smaller shaft didn't have these markings.


I would assume your car has them.
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'80 DL 2 dr

Below is a picture of how the driveshafts should line up when installed.





While doing an engine replacement of my first B27F and while swapping out the BW55 to the M46 I noticed ARROW marks on the front driveshaft that pointed toward the rear of the car. There was another ARROW (slightly rubbed off) on the rear driveshaft that pointed to the front of the car. Getting the arrows to line up makes sure the two driveshafts are lined up correctly at the splines. After that is done look at the picture to make sure you have the driveshaft installed correctly to the tranny & to the rear end. Good Luck!

Sincerely,
--
Nickvjr

1979 264GL B27F 122K

Features Added:

BW55 To M46, Central Locking System, 25mm IPD Front Sway Bar, 81+ Dash W/ Oil & Ambient Temp Gauges In C, Oil Pressure, Volts

Next Project:

Add Cruise Control