i just reworked a 400 for a friend of mine and all I did was put on a performer intake and a 780 vacuum secondary holley with that powermax 266 cam and some headers.. the trucks are nearly identical for weight and we run the same tires. that truck of hers pulls alot harder out of the hole than my 390 but cant keep up at the top end. with the exception of intake manifold selection, parts seem to be more readily available for the 400, and400's are dirt dog cheap compared to the FE.. like gashog said though, they are not nearly as stout as an FE... being kinda hard on things i prefer the FE.. LOL