I know in 85 the block was changed to allow taller roller lifters. There was no mention of rollerizing the valve train.

I think it was only the '93 Cobra but there might have been other limited production cars with roller rockers as well. There are a lot of people on this board with a lot more knowledge in this area than I have so let's see.

1985 was the first year with roller lifters. And was standard on every year there after on Over Head Valve Engined (5.0 & 351) (85 - 95) Mustangs.

The only production Mustangs to come with roller rockers was the Cobra models in 93, 94, 95. They were actually made by Crane and were 1.7 ratio aluminum.