I posted a query about the UL631 bulb fit a while back and am continuing the conversation. The problem is the Wagner made bulbs have a “flare” at the point where the upper part of the metal base meets the glass of the bulb. This is visible when compared to an original factory bulb made by GE. There may be others maker of original factory bulbs. I tried to install the Wagner bulb on several 65 and 66 Mustangs, and a 66 Shelby. None would accept the Wagner bulb.
See pic 1 – GE and Wagner bulbs –
The “flare” on the Wagner bulb does not allow it to be fully inserted into the socket to engage the two locking pins.
See pic 3 – Wagner bulb sitting in socket –
(Note: the socket used is from a 66 under-dash harness.)
This occurs on the two 64-66 Mustang under-dash courtesy lamps. The same fit problem is may be found on the 67 and 68 Mustang left hand courtesy lamp as they use the same bracket and may use the same socket. A GE bulb fits easily, engaging both locking pins.
See pic 2 – GE bulb installed in socket –
When trying to install the Wagner bulb, you are put upon to use force. This may cause the bulb to shatter. It’s called a safety hazard. My right hand thumb still has a small scar from a similar bulb being forced.
One recommended solution was to bend the socket retainer arms to grip the bulb as well as to hold the socket to the bracket.
This does not always work. What happens, with the bulb not installed, is if the arms are bent to hold the bulb, the bend will not allow the socket to be either installed in or removed from the bracket.
Filing the flange usually winds up with the bulb's glass broken.
I’ve been in contact with suppliers about this situation and their response has been “cool”.
I point out that Wagner is not a factory bulb supplier, so the use could result in a judging point deduction. This is not likely as the manufacturer’s ID is hidden by the socket, and the location requires some difficult contortions for inspection. For Thoroughbred classes, it’s a different story.
Until bulb’s sellers get a different manufacturer or a different designed base, the “flare”, my recommendation is when ordering this bulb, to ask the bulb’s seller who the manufacturer is, and if it’s Wagner, don’t order it, and tell them why.
Here are previous links:http://www.concoursmustang.com/forum/index.php?topic=7418.msg42067#msg42067http://www.concoursmustang.com/forum/index.php?topic=9819.msg58341#msg58341