A.C. Gilbert didn’t use standard bulb numbers for its products, so locating the correct bulb can be difficult today. Here is a cross reference chart between Gilbert’s American Flyer bulb part numbers and standard manufacturer part numbers.

If these numbers look vaguely familiar, it’s because one of those other brands of electric trains sometimes did use industry-standard numbers, and both brands used many of the same bulbs.
Catalog # | Name | Volts | Color | Gilbert part# | Equivalent |
all | Locomotives | 14 | clear | 440 | 1449 |
all | Cars | 18 | clear | 444 | 432 |
all | stations and buildings | 18 | clear | 444 | 432 |
8b | transformer | 18 | clear | 454 | 431 |
12b | transformer | 18 | clear | 454 | 431 |
15b | transformer | 18 | clear | 458 | 1445 |
16b | transformer | 18 | clear | 458 | 1445 |
18b | transformer | 18 | clear | 458 | 1445 |
19b | transformer | 18 | clear | 458 | 1445 |
30b | transformer | 18 | clear | 458 | 1445 |
592a | crossing gate | 14 | clear | 440 | 1449 |
596 | water tank | 18 | clear | 453 | 1447 |
658 | Sam the Semaphore | 14 | clear | 452 | 1402 |
720a | switches | 18 | clear | 453 | 1447 |
730 | bumper | 14 | red | 455 | 1447R |
750 | bridge | 18 | clear | 444 | 432 |
759 | Bell Danger Signal | 14 | red | 455 | 1447R |
760 | Highway Flasher | 14 | red | 455 | 1447R |
761 | Semaphore | 18 | clear | 453 | 1447 |
769 | revolving beacon | 14 | clear | 461 | 461 |
772 | water tower | 18 | clear | 444 | 432 |
774 | floodlight tower | 18 | clear | 453 | 1447 |
778 | street lights | 18 | clear | 453 | 1447 |
switch control box | 18 | red | 441 | 432R | |
switch control box | 18 | green | 443 | 432G |
A modern alternative
You might also consider upgrading to LEDs in your American Flyer trains. LEDs last longer and use less power, so you don’t need as powerful of a transformer.
This list is awesome thanks for posting it I was going nuts trying to find the right numbers for stations thanks again