[CDickey]

So the tach on my '00 Speed Triple decided 9 years was enough and quit working on me. I intially thought it was a wire issue because it wouldnt work properly after I had the cluster apart but after some "adjustment" everything would work. Well adjustment dont work anymore. I have power to the back of the tach and the continuity of the harness is good so I'm thinking its the tach itself.

Anyway. Are there any aftermarket gauge options, i.e. Autometer, that would work? The installation instructions from autometer indicate that the tachs are calibrated for 8 cylinders but you can move the dip switches and set it for 4cyl or 6cyl. Oddly enough there is no dip switch set up for 3 cylinders.

 

[DEcosse]

I can't really see any upside on replacing the tach with after-market - would suggest to just look for a used OEM replacement.
Speedo I could certainly understand - to replace the mechanically cable-drive unit with an electronic instrument. I've actually done that with a pro-meter but it wasn't trivial. (if you search you can find the 'how-to')
Now I believe the way to go would be to use a Sprint ST speedo and front wheel sender (which is actually mechanically a direct fit to your S3 wheel). Normally the sender inputs to the ECM which in turn drives the speedo, but I think that the sender could drive the instrument directly in a retrofit situation.
I would suggest a nice project would be to find a used ST panel and swap out both the tach & speedo gauges and re-wire accordingly. I can help you with the wiring requirements if you need some help.
Then you'd also have a matched set of gauges in the S3 cluster (which I always liked aesthetically on that vintage)