Thanks for the update. I never got round to fixing the second cluster/tacho so I might try this method. Did you use some jumper wires or something for the direct connection? You'd have to scrape away at the trace and tack a conductor onto it yeah?
Someone will have an idea, i'm sure. Pretty sure there are different markings on the block that identify which R-chassis it came out of, and other little identifying marks. I believe the oil pump sleeve on the crank is different after R32, etc.
The FAST system is just Nissan's build database, so it only shows how your car rolled off the production line.
You can check the options decoded from the "Model", but GTR registry has already translated it all for you.
Certainly not the '95 in your profile hey!
FAST is the source of all truth but Mark pulled all that info and put it in the form of http://gtr-registry.com.
You can bang yours into http://gtr-registry.com/en-bcnr33-vin-table.php and you can verify that it is indeed a s3, and all the option codes from FAST are translated too. (large front spoiler!) =-D
Funnily enough, two weeks ago my replacement tacho is now doing the same thing. I'll solder everything and see what happens. It makes sense that it's a dry solder joint since it's a sudden yet intermittent fault.
The EPC online has been around forever but Mark made this more recently: (https://www.sau.com.au/forums/profile/95792-sin/)
http://gtr-registry.com/ choose car, then vin table.