This video presents a possible solution alternative for those in need of a replacement 89661-60250 ecu, although the project is incomplete and will require additional problem-solving.
In a troubleshooting saga featuring a malfunctioning 89661-60250 ecu (1993 Landcruiser Prado RHD Japan import, automatic, 1KZ-TE turbo diesel engine), I spent some time and re-pinned the ecu harness to accept the newer 89661-60560 (1998 Landcruiser 90 or J9, 1KZ-TE) to see if it would start/run the engine. The original ecu is very scarce, and I could not locate another one, so this allowed me to determine 100% that the original ecu was the culprit. For anyone stuck in the same jam, the 60560 ecu may be an option if it were purchased along with an immobilizer, key, and keyring, or if the 60560 ecu was re-programmed to jive with a non-matching immobilizer/key/keyring.
If the transmissions are different, there may be some challenges there to make it communicate properly with the ecu, I didn't get that far to test. There are also some pins that don't seem to have a home. On the 1993 ecu, there is only one "SP2" pin, whereas on the 1998 ecu there is an "SP2+" and an "SP2-", so I did not get to test if either one of the 1998 pins will be what the 1993 harness needs. There are other ect-related pins that are differently labelled, and may function in a different manner (snowmodes), and no-one has been able to define for me what the "DG" pin is on the 1993.
However, I thought I would post this up in case someone wants to continue along this path and finish it, especially for swaps or just for a possible new solution to a very hard-to-find ecu.

Two dealers/shops and two electronic shops were unable to solve (determine and repair) this 1993 ecu. I may have another go at it this week with my microscope and see if I can spot something amiss.
In the meantime, the 60560 may present a solution for some folks who are frustrated at a lovely 1993 Prado that will not run due to the ecu blowing it's aging caps and traces, and having no replacement 60250 ecu's anywhere on the new/used market. Just know that you will have immobilizer challenges since the 1993 did not come with immobilizer equipment.