I have a 400 in my 79 F150 and currently am in need of a set of breather caps. Can't seem to find them anywhere. When i did my engine swap i had the factory turn in one for the oil fill cap and a regular grommet and blow by tube that went down to the frame rail on the passenger side. Anybody know where i can get a new oil fill valve cover cap? Running the stock valve covers

 

There was only one oil (breather) cap originally, located on the left (drivers) side valve cover. The smog valve fits into a rubber grommet on the right (passenger) side valve cover.

You shouldn't have any trouble finding the oil cap, because...the same one was used from 1968 into the 1990's on a gazillion different FoMoCo vehicles.

E3AZ-6766-A (replaced C8AZ-6766-A ~ painted black) .. Oil Cap - painted yellow (Motorcraft EC-682).

1968/90's myriad I-4/I-6/V6/V8 FoMoCo vehicles.