89 where are you from, because some years/ECUs may vary slightly depending on market.
For instance, I don't THINK the US got a version with 02 sensors UNTIL the Cal-Vin.
FWIW, my 00 Jackal had an open-loop system with the ECM under the seat (well, more under the left sidecover, but technically that was right below the seat).
I think I could have easily placed a Cal-Vin seat on the same Jackal...and considered it at one point.