Those oil coolers were standard on 1800s for years. I had one on the original B18 that was in my '67. It used a unique Y-shaped lower radiator hose, one branch feeding the water pump and the other the oil cooler. At this point, I don't remember the squigley tube, but it must have had something of that sort -- the radiator hose wasn't nearly long enough to reach the cooler directly.

I have not seen one that wasn't on a B18 in an 1800, though. I chose not to transfer it to the several B20s the car has had since, and ended up giving the whole mess to a friend last time we moved.