These unit have a "known concern' relating to the wire harness for the throttle body, and a fuse that does not show in earlier schematics, for the throttle body. That fuse being blown or removed will set an e-23 code, as well as if the wire harness is pulled apart or the pins pulled out of the connector right near the throttle body. Often near where it bends into the rest of the harness.
There is also the concern of the changes to the throttle body and where/and the type of the pressure sensor mounted to the throttle body.
I would point out (swoop) that MCFA did not have a Nissan K21-k25 powered tier 1 truck, (tier 1 was 2003, and a 4g63-4g64 powered truck) but that the 2004 version was indeed a bit different from the 2005 and newer units as to where the diagnostic connection is found (among other changes).
It is also worth noting that not all MCFA trucks had an OBD2 connection in/under the cup holder, and I am pretty sure I have seen some that had a different style of connection that was not shaped with the OBD2 style angled sides.
I guess It should also be pointed out that swapping of the ECM from a slightly later serial number (or different model) is not recommended as they will plug up but then throw errors as they use differing schemes for the throttle body fuel pressure sensor, and ratios in the transmission sensor.
Yansteven, the legality of sharing copyrighted information is done by each country, so what is of concern to someone in the USA or Australia, may not be the same concern for someone in some other country.

ey? Language barrier... Ey? 'nations separated by a shared tongue' Ey?

Now I get to throw in my own $.02USD W.A.G.:
in the relay box that you find in the engine compartment, swap the relays around (or replace all the relays) and see if it changes. if you have an all LPG truck, the fuel pump relay is a 'spare', as LPG does not need a fuel pump.