Does anyone know if a 07' or 08' F150 4.6 engine will fit in an 98' F150 with a 4.6 and what would have to be changed out?

 

I think it'll physically bolt in... and that's about it. Everything north of the heads will have to be swapped over from your 98'. Might not be a bad time to swap over to an 01'+ PI upper intake manifold and get a tune while you're into it.