Without looking in my owner manual for my 67, I don't think 1157s are for backup lights. 1157s are double element for taillights and brakelights. The pins are staggered differently. Backup lights are 1142.

Last edited by Redvert67 (11/29/2015 1:07 PM)

1157's are the dual element bulb used in late model cars and 1156's are single element that are used in late model cars. If the bases are the same, the 1156 will use a little more power and be a little brighter, shouldn't really be an issue with heat because they are only backup lights.

Also, since the contact in the socket is spring loaded, it is possible for it to become dislodged and not let the bulb go in, or if it does go in, it can short out.  You can put a little tension on the wire by pulling it slightly from the back side of the socket to make it easier to get the bulb to go in.  You should feel the spring being compressed when the wire is pulled.  That holds the contact down until the bulb is in place.  Be sure the spring is still in operating condition.

Others are correct that you need single element bulb with symmetrical lugs on it.

I use dielectric grease on all bulb sockets.  Makes it easier to install the bulb plus helps keep corrosion to a minimum.

Since the back up lights on my 65 are absolutely useless, I am re-doing the rear valance with a couple of "Frenched" fog lights instead. Maybe I'll actually be able to see something behind the car on those cold rainy nights in Michigan.I am putting a relay in the circuit with a real feed wire so they are nice and bright.