Which years 5.3 liter engine affected by O-Ring failure?

[Amanda4461]

Anyone know which specific years the 5.3 Liter engines were affected by the disintegrating O-Ring at the oil pump suction connection? I assume that GM corrected this problem eventually, but figured I would rather be safe than sorry. If mine falls in the "bad" years, I'll change it out next time I feel like getting nasty.
Thanks!