[smj999smj]

It did throw a code...a transmission code...when the O/D light was flashing. You could follow the transmission self-diagnostic procedure in the service manual to retrieve the code if it isn't still flashing. As far as the speed sensor, the typical code is P0500 for a vehicle speed sensor circuit malfunction, however, that doesn't necessarily mean it's the sensor, itself. If there was a problem with the speedometer circuit in the cluster, or between the cluster and speed sensor, it would still trigger the same code.

 

[smj999smj]

When it starts acting up, you should try banging on the dash or tapping on the cluster to see if it has an affect. If it does, it's the cluster and not the sensor.

 

[smj999smj]

As far as to why both failed at the same time, there is no answer other than coincidence. As far as the mileage, if memory serves correct, it is stored on a soldered chip inside the cluster. Personally, I wouldn't install a used cluster as these clusters have been prone to problems, usually caused by solder breaks on the circuit board. I would send the original cluster out to a place like Circuit Board Medics or Mr. Whizard and have it repaired; this will ensure your mileage is the same. With a used install, you will likely get the mileage that was on the donor vehicle. On later Nissans, they stored the mileage in the ECM.

www.circuitboardmedics.com

http://www.mrwhizard.com/

 

[smj999smj]

It's not hard. Mostly Phillips head screws. I think there are three plugs on the back of the cluster. With all of the cluster problems they have, I would imagine there has to be some vids on YouTube on how to R&R the cluster. Another issue with getting a used one is getting the "correct" one, as there were several different clusters that year.