I have a 97 150 4.6 4x4. My engine needs to be replaced. Is a 4.6 from a 2000 or newer the same as the 97?

 

2000 and newer should have PI heads. If you transfer your coil pacs over and use your wiring harness there will be no problems. You will need it to be complete with intake since your intake will not fit the PI heads.
I just installed a rebuild with 2001 Windsor heads and it is working just fine. I found most of the 4.6L motors from 2000 on are Romeo blocks. The only problem you will have is be sure you get the flex plate with it, they use 6 bolt cranks. Otherwise it should be no problem.