[olddog]

The 4.6 DOHC cobra engine is already wider and taller than a FE or 385, as said earlier. However the 5.4 is a taller, wider deck, by roughly an inch. The 4.6 DOHC cobra is an aluminum block and already heavy (from what I find on the enternet about halfway between a 351W and an FE). Not many aluminum block 5.4 were made which is going to put it about another 100 lbs more, if you use a cast iron 5.4 block. Anything can be done, but I'm sure the 5.4 would be harder to fit in a Cobra.