As said union is turbo oil feed, but 2wd oil feed is better, as oil is cooler,(not being heated up on it's travel all the way through the engine).
On 2wd the temp gauge sender is at front of head near turbo, the ECU temp sender is on the plate mentioned at the rear inlet side of head where the 1/2" water pipe joins on, this is ALSO the place where the 4wd has a temp gauge sender as well as the ecu sender, hence no hole in front of head turbo side.
So you can see if you can drill/tap a hole for temp gauge sender here in the 2wd plate or get a 4wd plate, as this already has it,
tabetha