ok sorry, here's a picture of my display. I just looked it up under my bought items on eBay... the seller that I got it from is no longer an eBay member, so I can't just post a link to a similar looking display with a great degree of certainty.
As I said, the PCB is too big to be mounted inside the gauge, and also, it does have an unsightly scratch on it now.
The main issue was not knowing that it required four inline 1K resistors on various pins to work, as well as that I had trouble finding the correct library. Documentation was zero, and it was only thanks to the dogged determination of some tech blogger and his posts about it that I managed to get it to work.
For this project, I'd really rather not use it.