I knew you would know some stuff
@Superhawk996 The n in 914n6 stands for Nissan
but yes it's a coolant crossover pipe.
The hole surface has radial machine grooves, as all the others (gauge & ecu temp senders, etc) like a special cut drill bit, then I would assume threaded after.
If I can clock this it would be much better than piecing together a bunch of NPT fittings. This is heater out @ 5/8" and feed to the VW coolant reservoir @ 5/16". Steel pipe is actually 19mm OD.
I thought a double banjo stack would be sweet but no luck finding all the pieces, plus I doubt I could get it threaded straight anyways.
I'll look into ORB fittings next.