Hi, I have a 1977 F-100 with the 300 CID 6. The head has 3/8 rocker studs with locking nuts which stay where you adjust them. I need a valve job after half a million miles and I came across another head that looks just like mine except it has 5/16 rocker studs and the nuts are not self locking, there is an additional locking nut. Can anyone tell me if this is pre 1977 or post 1977? I cant read the casting number to tell what year it is but I belive it is a 70's vintage because it is adjustable. The rockers look the same.

 

Can you post a picture of your setup?

My '81 had 3/8" studs that tapered down to 5/16". There was only one nut on them.