Update
Well I have a little update. Prior to calling the tech line I had written their generic email address to ask about the proper fittings but did not get a reply until after my phone conversation. So I politely replied to the salesman's email reexplaining my questions, answer about not using with diesel, etc and asked if AM carried a different isolator that would be better. The salesman wrote me back today and his response is:
"To the best of our knowledge, we have not had any high pressure isolator failures related to diesel fuel. Our service department prefers not to install them on diesels, because we have never done any internal testing on them in diesel applications. That said, they prefer not to recommend them in diesel applications, simply because they have not definitely confirmed their compatibility. I have also not heard of any pressure spikes causing premature failure of either the isolator or gauge on your vintage Power Stroke (or any Power Stroke, for that matter)."
So it seems there is a little internal disagreement on the issue. Makes me wonder if the tech department was not simply trying to upsell me for more $ although that seems an odd thing from tech support since they are not sales driven but who knows.
So, I think I will keep the gauge and get it hooked up.
So, what size and type is the fitting on the FPR if I remove the schrader or is is possible or even recommended to attach it to the schrader?
Thanks guys.