PART NO.  SPL.PAGE  DESCRIPTION                                                            
2H4732    15.O.1    Bulb (flasher warning light, dash, 1500)
2H4732    15.O.3    Bulb for panel and warning lights (7) -(dash, 1500)
2H4732    TC.N.10   Bulb -(flasher warning light, flasher-horn controls, electrical,
    Twin Cam) -changed to BFS987
2H4732    TC.O.1    Bulb Bulb -speedometer illumination -(instruments, Twin Cam) -changed
    to BFS987
2H4732    TC.O.1    Bulb Bulb -beam warning light -(instruments, Twin Cam) -changed to
    BFS987
2H4732    TC.O.1    Bulb -revolution counter illumination -(instruments, Twin Cam)-
    changed to BFS987
2H4732    TC.O.1    Bulb -ignition warning light -(instruments, Twin Cam) -changed to
    BFS987
2H4732    TC.O.2    Bulb -fuel gauge illumination -(instruments, Twin Cam) -changed to
    BFS987

BMC part number 2H4732. This is an E10 standard screw base bulb for Instrument Lamps and Warning Lights. Original issue was an incandescent bulb with 2.2-watts power consumption and rather meager light output.

Watch part numbers and power ratings, as other bulbs in same size may be as low as 1.2 Watts. The E10 standard is for physical size of the glass globe and metal screw base, but can be made in a wide variety of voltage and power ratings.

See article for Faulty Parts FT-019 having issues with worn out tooling causing loose fitting bulb sockets and subsequent remanufacture of bulb sockets with too-small barrel so standard bulbs do not fit (but bulbs with undersize threads do fit).
    Original  bulb  thread   OD = 0.367-0.370 dia (not quite round) good fit.
    New (incorrect) thread OD = 0.358-0.361 dia (not quite round) loose fit.

Alternate part numbers:
BFS987 - BLMC new part number
GE 26095 - type 258 - 4-watt
171-000 - Moss Motors USA

type 52 - 14 volt, 1.4 watts
type 258 - 14 volt, 3.7-4.5-watt
type 428 - 12.5-volt, 3.1-3.5-watt
type 1446 - 12-volt 2.4-watt
type 1449 - 14 volt, 2.8-3-watt

For a while around 2020 this size bulb could be found as 3-watt incandescent for a little brighter light (with a little more heat and possibly shorter life), brand Heshaoc, 12 Volt, 3 Watt. When searched in early 2021 they would be out of stock with no reference to when they might be available again.

Also available as custom built (expensive) 5-watt and 10-watt Halogen bulbs for much more light, and much more heat, and certainly shorter life.

Also available as 5-watt (equivalent output) LED bulb. I have personally found these (from Moss Motors) to be repeatedly short life, which is unacceptable for an expensive part. They will burn out quickly with over-voltage (like a run-away alternator or generator), and apparently they do not like vibration. Having gone through at least a dozen of these LED bulbs, they have all failed, not a keeper yet. You might have better luck with a different design from some other source.