Yes, it's leaking from the primer pump.The filter genuine filters that go on there are branded parker I think. I would assume that parker make the filter head and bowl as well.
Have you got a leak on the hand pump? I notice that your filter is plumbed between the lift pump and the injector pump as the early tractor were. There was a program to change the plumbing so that the filter was before the lift pump. The rubber hand primer didn't cop the pulsations and pressure like it does with the way your tractor is set up now.