Sorry guys, I goofed!
Our parts guru Dave Gallon pointed out to me that part #16 is NOT the grounding wire from the block but it is the one that JPMOSE identified as the cable going from the firewall to the engine/transmission. The original p/n of that one was indeed:
110 540 01 31 replaced by
109 540 01 31 replaced by
116 540 02 31 or 116 540 05 31.
So what about the one on the block behind the power steering pump?
He pointed me to page 82-20 in the 1968 BBB which identifies this grounding strip as p/n 111 540 00 41. See attachment.
It is part of the "Interference Suppressor" kit when a radio needed to be installed. It is indeed routed from the block to the
"upper lefthand oil cooler fastening bolt".
Unfortunately for JP this p/n is also NLA and the only solution is to fabricate one or find one at a junk yard. Apparently the cable was also installed in several other models from that time period. See text enclosed in red.
Also note the remarks about the grounding strap for the hood (in blue).
Dave Gallon thinks that the strip was necessary to bring the oil cooler/radiator to the same electric potential as the engine to prevent radio interference. Attaching it to the side member does no good. But he mentioned that this was frequently done by owners and mechanics who did not know because the strap interferes with easy removal of the battery.
Now, who is going to change the wire on their 280SLs?
{I corrected my initial post to prevent any future misunderstanding}
