Hello,
Can someone tell me what are the fittings for the fuel regulator / fuel hoses named ?

I'm looking fittings to add variable fuel regulator, and as I don't want to cut the original fuel lines, I need the use the actual fittings.

They are a metric compression fitting. I found a box of Bosch fuel injection metal fittings at a shop foreclosure a few decades ago that fit the XJ40 and X300 but I never measured the sizes or threads.

Should be the same as old VW, BMW and Mercedes?

Thanks @motorcarman

I have measured with my caliper, it's 14mm, and the thread is 1.5mm.
So, M14x1.5 !

Could not find it in France, so I bought them in China.