I have found the stock gauges were not too reliable, atleast on my gen1s. I have changed out the sending unit and gauges. I left the same sending unit and switched the gauges out and got a different reading. But the ones I was using were around 13-15 years old though. Mine do read consistant, I just dont think they are exact. I know a couple people used aftermarket gauges. Someone will chime in and give you more info.

I just want to tell you both good luck, and we're all counting on you.