Toyota 1MZ-FE 3.0L Engine compatibility

[LEX200108]

I have an 2001 RX300 with the Toyota 1MZ-FE 3.0L Engine. I see this engine was installed in many Toyota's and wanted to know if the engine was the same in all Toyota/Lexus? I realize the wire harness and some of the electricals may be different, also front wheel drive and AWD engines appear to be different. I need a FWD Engine, can I use it from any of the FWD Toyota's/Lexus or is there any mechanical difference such as cams, mounting assy., etc., thanks!

I'm also currently looking at a wrecked 99 Lexus ES 300 with the same FWD engine. 

[LEX200108]

I see the 1MZ-FE 3.0L used in many Toyota's and Lexus. I need an engine for a 2001 RX 300, will any 1MZ-FE 3.0L from a different car such as the Highlander, other Lexus cars work if installed in the RX300? I realize the wire harness, and other addon's may be different, I am just talking about the engine itself, thanks