They arent forged at all, that's why they left off those years when they mentioned it.....

 

for the 1985 5.0 model year ford started using forged pistons to replace the previous years of using sandcast pistons. but in 1986 they were using the new forged flat top pistons and in 1987 the switched over to the dished top pistons up to 1992 and im sure every one knows that in 93 they went to "hyperpathetic" pistons.

this is in my own wording but i got the info from a site so i guess the forged pistons were from 85-92