Anyone know who makes umbrella valve guide seals that are a "drop in" for the Vortec heads? The Vortec guides I have are over 1/2" diameter, closer to 9/16". (no dial calipers here) "stock" seals are red on exhaust, black on intake, have a steel outer shell (probably just as a retainer) and a small spring to keep the seal tight against the valve stem. http://www.compcams.com/information/whatsnew/NewsDetails.asp?ListHistoryID=-644070045 Shows the diameters, but I really doubt .53 seals will fit a guide that appears to be about .55". Hopefully Vortec umbrella seals ARE made by someone!