Valve stem seals, anyone in the know?

[Octanox]

Im getting ready to change the valve stem seals in my s-10 (4.3-262),
the seals that im used to seeing in my previous experiences are a type
of "umbrella" seal, these things the parts store gave me are tiny little
9 cent "o" rings. I havent peeled off the rocker boxes yet to try to see
the old ones, I havent found anything in the s-10 forums that help,
even the part store online repair info shows a larger looking seal.
Is there something Im missing?

[maxwedge]

The ones I used from GM were improved umbrella seals and o rings.