The lamps I got recently were 12V 2W. I also have a couple of 24V 3W but they are probably overkill for an indicator, I suspect they are intended for truck interior lights, ePay seems to have 24V lamps of this type from 0.6W to 3W, as well as 28V 2.8W and 30V 1.2W.
I found these by searching for BA7S & the voltage.
David