I have three different spfi manual trans wagons, all are stage 2 (post wiring changes) and I need to know if the ECUs can be swapped around between them. 

Pictured are the ECUs in question. All have different numbering on the stickers.

After some extensive searching I’ve been unable to find a thread which answers my questions. Links to threads which I may have missed are appreciated!

Those are all the interchangeable.  Look up the parts numbers at a subaru website and you'll find them listed as superceded under one part number and/or applicable to the same vehicles. 

5 hours ago, idosubaru said:

Those are all the interchangeable.  Look up the parts numbers at a subaru website and you'll find them listed as superceded under one part number and/or applicable to the same vehicles. 

Thank you, this saves me a lot of headaches.

I didn’t know I needed to search them on a Subaru website. Hope this is able to help others as well!