According to my 230SL parts book, the part numbers for the crankshaft are:
Manual Trans:
127 030 70 01
Auto Trans through engine # 5119:
127 030 44 01
Auto Trans from engine # 5120:
127 030 71 01
Additional note: "...with counterweight, flywheel, main bearing shells and connecting rod bearing shells".
I do not see any part number for the crankshaft only (and the Benz Dr. says you should get the flywheel with it anyway).
-David
P.S. The motor number for my early '66 auto trans. is only 3868, so motor number 5120 is probably a fairly late 230.