Side Marker Bezel
That new socket needs to be flared/swedge in place as the originals are. Take the bulb out to do it. Here is how I did some before, We had the tool.
I cut a slot in an old deep well socket that fit the flange on the back so the wire can slide down in the slot like a o2 censor socket.
Hold the bulb socket in the marker light hole with the socket you made as a backer.
Then I use the ball of a small ball peen hammer and put it over the bulb socket. Then pressed down in a press. Going to a larger ball peen until I could press it flat . I remember on some that were corroded I had to make washers because the hole was to big.
They are swedged in place. Now my son made a tool to do it so we can have our original housings rechromed