Do you own a big wooden spoon Pete?
They would be blue on that one.
The way to settle the colour thing is to ask old Ford mechanics who were there. But no-one believes them! (and I do not mean me).
The Super Major was Single Acting Hydraulics, the response to draft signals worked on the "push" on the top link, "pull" on the top link caused the lift to lower.
New Performance hydraulics were "Double Acting", "push" on the top link causes the lift to raise, "pull" causes the lift to lower, a greater "pull" causes the lift to raise.
If you had a long mounted plough, the signal to the lift would be constant "pull" because of the length, with occasional sharp "pushes", with the NP system, if draft increased without the plough being able to create a "push" on the top link, the extra "pull" as the draft increased caused the raising correction.
The 2000 was the only tractor of the "New" range to retain Single Acting Hydraulics. All the others had "Double Acting, that is why the 3000 and 4000 have a draft spring that is in a housing so it can work in both direction. All the tractors have procedures for setting the force applied to the spring and you cannot just tighten it up.
The 7000 and some 5000 tractors had "Load Monitor" sensing which sensed the load on the pinion in the rear axle. This was a far better and more sensitive way of controlling draft forces on long heavy implements. It would work on external rams too. If you had a trailer connected to the tipping pipe and drove down the road with Load Monitor selected, you could find, when you reached a hill, the hydraulics would lighten your load by tipping some of it off!
It will never fly said Mr. Wright.