There's a chance it's the original ECU. Since it meters off the MAF, it could have adjusted sufficiently for the different engine displacement. If you're swapping it, keep in mind you'll need to swap the immobilizer bits, too.
There's a four letter code on the ECU, like DESK here:
https://encrypted-tbn2.gstatic.com/i...HDwvkvR_VxAOgA. Trawl the web for it and find out what car it comes from.