Hi Fabs, it will be npt, most temp senders are 1/8th npt but usually the sump has different size like 1/4npt so you need an adaptor to fit it
cheers Richie
this one?
1/4'' NPT male to 1/8'' NPT female
or here in belgium the sender can be in metric? so i will take 1/4npt female to M10 male if avaible