I have an 06 Dodge Ram 1500 four-door 8-ft bed 4x4 5.7! What do I have to do to put an 05 5.7 in it?

 

If it is a 2005 1500 5.7, then all you have to do is drop it in, but you'll need to turn off MDS in the PCM with a tuner. If from a 2500/3500, you'll need to open up the EGR port or turn EGR off with a custom tune (not likely since it is emissions control). If from a 2005 LX, then you'll need to swap intake, oil pan, front cover and accessory drive.