Hmm; looking at pics on ebay
https://www.ebay.com.au/itm/28270248...4AAOSwmj5ehfe4 the MKII high pressure lines appear to come fitted with a green O ring per
https://www.globaloring.com/oring-colors/ . It seems the only way to get them may be to buy the whole high pressure line. But green O rings are usually Viton and I have a whole boxed assortment of green Viton O rings so I might try those. Only issue is this I have an aftermarket Kelpro one that has a black O ring supplied (probably Nitrile). I bought the Kelpro although it was more expensive than the genuien Ford one as I also have a leak at the loop and I thought the extra support bracket on the loop that the Kelpro has might prevent vibration and further leaks. The high pressure switch that it common to the MK I and MK Ii appears to use a green viton seal too per
https://www.ebay.com.au/itm/23177128...UAAOSwbBxgdl-Y so that suggests a Viton seal should be OK using either fluid. Of course the change in fluid specs might meet that there has also been confusion over the correct O Ring material and I am going to be stuffed whatever I do.