Are the late model 302 and 3.8 and 4.2 rockers all the same or are they all differant. If so what are the differences

 

wrongday j: I see that you have roller rockers down as one of your mods. I have a set of 302 1.73 roller rockers and was wondering if I could use these on my 4.2. I have heard that the 3.8 heads are just 302s with 2 cylinders choped off, are the 4.2s the same?