In the currently running thread on using LED's in place of incandescent bulbs, a member posted this reply:
Pingmam; If you're doing PW Lionel that have bayonet type bulbs, you can buy bayonet type leds that just plug in like a regular bulb from Town and Country Hobbies for $2 each, cheaper if you buy 60 pieces. I just did my 2500 series cars and work fine.
I even put them in my 2343 F3s. Vic
Evidently, you can buy bayonet LED's for passenger cars. Contact Town & Country Hobbies for the correct LED for your application.
You can also check with new forum sponsor, Train Electrics, since they carry bayonet mount LED's.