Jim -- Maybe Jerry can answer this -- IF you have the umbrella caps, I don't know how you can tell if the O-rings are also installed short of pulling the head to drop the valves... I would think the keepers hide them.
If you don't have umbrella caps, O-rings are *probably* there.... If there *are* umbrella caps ....Hmmmmmm. But if your head got done by the same guy who did mine, I think if I saw the umbrella caps that I would think pretty hard about pulling the head to be sure the o-rings aren't there, too.
Unless the White Wizard from Tennessee has a better idea ...
Not the White Wizard at all, But I changed valve springs on my 5.9 Cummins by making sure each cylinder was at TDC before compressing the valve springs enough to remove the keepers. Also many years ago I changed the valve seals with heads on, on our 1988 Dodge Dynasty's 3.0-liter, V6 Mitsubishi engine using a jury-rigged spark plug with an air chuck welded to it. Lesson learned, too much air will rotate the engine, gotta be CAREFUL and don't pull all the plugs at the same time.
Although I've had my '51 for over a decade now I've luckily not had to think about valve stem seals...yet.
Good Luck,
RonR
