I'd have to disagree with the last two posts. The gauges are not backlit or translucent. Light simply shines on it from the sides. At least on 550's this is the case.
And having vinyl printed is not per sé better than printing a good quality inkjet photo yourself. I have bit of experience in both vinyl printing and screenprinting, and do a lot off proffesional printing for clients right now.
If you (or a friend) have a recent inkjet printer, and buy some good quality paper, they will not fade for at least 50 years and look great too. Epson has vinyl that goes in regular inkjet printers for my printer, i'm not sure if they have it in smaller sizes too (my printer use 44" rolls). But for my own gauges I used Ilford Pearl and glued it on with spraymount.
Just go to your local photographic supplier and buy a testpack with different types of paper for a few dollars and make some tests. I suggest not using fibre based or photo rag papers because they might absorb water/moist.
