The transmission and motor mount pattern is the same on the 5.4 & 4.6. The trouble you will have is everything else. The 5.4 is taller and wider than the 4.6 so consider that as far as making it fit and hooking everything up including the exhaust. The mark VIII engine is a DOHC and the pick up engine is a SOHC and although you can replace one with the other it will not be a bolt in swap. You will have to change the engine harness and swap the PCM. Then you have to deal with different electronically controlled transmissions and they are controlled by the PCM so swapping the PCM for the correct engine may not be the correct one for the transmission you want to use.