Just bought another F series today. It's an 89 F250 4x4 SC 460FI auto. There's a flat bracket with 3 studs mounted to the top of the R side valve cover. Doesn't seem like anything was ever mounted to it. Nothing is plugged and every thing works. Any ideas? Thanks

 

Does your truck have an after market air filter system? My 1985 has a bracket like you describe on the left (driver side) valve cover that holds the original air filter housing.

 

could also be the bracket for the throttle cable linkage stuff cover. just an idea. not sure this year would have it but my 94 does. a picture would really help