Oil pressure stewart warner sending unit

[Geezy]

Hey Guys,
Not sure if posting in the correct section, so mods please move if not. Need a little help with fitting sizes for a
a gnx reproduction cluster with stewart warner gauges and need to know the fittings and sizes to install the sending unit. I have tried to look on the site but no sizes come up! Id like to keep the oems sender and just add the stewart warner sender
Thank you in advance