I have a good 4.6 with trans and also have a 5.4 trans. If I want to swap the 5.4 trans to my 4.6 what all is involved. I've read that it is a more heavy duty trans and thinking if mine starts to go bad if it is a possible swap

 

It depends
What model year trucks are we talking about? Were they both 4WD? Did they both have the same rear end ratio? More details please.

 

They are both 05. 4x4s

 

I suppose the 5.4 version of the 4R75 transmission is heavier duty, but a properly maintained 4.6 version will last you a good while, anyway. Toss a transmission cooler in (or upgrade the factory version) and you’re pretty much good to go.

 

I am not a trans expert.
Make sure the bellhousings are the same. I believe the 5.4 and the 4.6 have different mounting for the starter motor. My 2007 F150 with a 4R70E trans has a three bolt starter mounting and I seem to remember that the 4R75E has a two bolt mounting.