I called Advance Auto to buy replacement valve stem seals. They said they have 2 diffrent brands, Felpro and Seal Power. Which is the better of the two? What type should I get? Anyone know of better aftermarket ones and where to get them? Teflon or Rubber? NAPA said they could'nt even get them. Also I read on a post that there are different sizes. I have a 1966 Mustang stock 200 I6. Should I just get the umbrella style or is there a better seal out there. Any help would be appreciated.