wire/lamp identity??

Trying to identify a small lamp in its own harness located on the drivers side of the dash. It has a solid dark blue and then a blue with the white trace. It is in a moulded plastic socket. I know my 72 Demon had all the other bulbs just turn into the clusters printed circuit system. I have replaced my cluster with all separate gauges and I ran across this one bulb which does not appear to be part of the printed circuit cluster??? Looking on my wiring chart, I don't seem to find this?? Anybody know what it is?? Thanks....