I replace both of mine in the 80 240 and 85 300D. they are pricy when buying the whole assy with the Ignition switch.
on this page you can see the Lock assy comes w/o the Ign switch
123 462 28 30 Neiman $49.25
The lock assy with the Ignition switch
126 462 07 30 MBZ $207.25
1980 Mercedes-Benz 300D Sedan - Steering System - Page 3
This page shows the two type of Ignition switches. one the early style with the exposed pins, and the later style with the pins in a cup.
116 462 00 93 Kostal (exposed pins) $72.00
205 542 01 04 Kostal (Pins in cup) $38.50
1980 Mercedes-Benz 300D Sedan - Ignition - Page 1
Ordering the Lock assy w/o the Ign Switch, then ordering which ever switch your yr uses, is cheaper than ordering the whole assy with the switch.
I ordered one w/o the switch and used my old Ign switch in our 80 and did the same for the 85.
The Lock assy is the same exact part. I have three or four old ones from various years, and can`t see a nickles worth of difference. they are all the Neiman/Valeo brand.
I would recommend to buy the Keys and Tumbler from the dealer using your Vin#.
Check it out.
Charlie