I tried getting at it from the front and the knob came apart
I think the smoked plastic goes towards then then white paper then the clear plastic then the black ring
After a bit of poking around, I realized the bulb holder slid off pretty easily. The holder clip is the ground and the wire clips onto the tuner.
It appears to be a #240 bulb - 6.3V @ 0.36A.
Specs:
http://www.taillightking.com/images/...0240%20USA.pdf
All I had handy was some #1847 (long life #47) and an LED equivalent. They only draw 0.15A and I expect are not as bright.
It works but is really dim.
