Replacement taillight socket too small for bulb
 

Bought replacement taillight housings years back and the light sockets are too small. What can be done about that?

It's probably the chinese bulbs. Try a different brand.

Where did you buy the housings? Though certainly not cheap, Trim Parts makes an exact reproduction of your taillight housings. That may be "what can be done about that".

I bought Trim Parts tail light housings for my 65 coupe. I have the back up light option. I had a problem with one of the tail light sockets. ( not the bu socket ). It didn't have the correct channel for the bulb tits. I had to file down the tit on the bulb slightly to make it work.

I had the same problem and used same fix as woodsdesign reported. Break out the file.