Engine oil cooler feed line insert.

[Lynn Eades]

Good advice Rob. I fill most filters that hang vertically as well.
Malcolm. I have a couple of those fittings that have an internal taper cut in the end of the tube. (not sure what for)
Alistair, they appear to be made up as per Malcolm's drawing with a tube pressed in or sweated into the enlarged bore of a standard fitting (same as the short fitting in the other hole) This could be made with a current std. fitting. except that they would sit slightly higher because of the extra length in the spanner hex. I have not seen one like yours, before.
When Andrew Rowe spoke about a threaded plug in the horizontal hole, that is because the Australian (LP2/2a)carrier fittings do not have the long tube. They made it a total through flow system (all the oil must go through the cooler or the bypass valve to get to the engine galleries)