My C30 keeps burning out the left low beam?

[7dee2]

My 72 C30 (DD) keeps burning out the left low beam. High beams work as do all the other lights including the right low beam. The lefts seem to work fine when first replaced. I rarely drive the truck at night but have gone through 2 used good bulbs in just a few uses. What could be causing these to burn out so quickly?

Thanks,

[7dee2]

I guess I posted this in the wrong place to start. Appreciate the move to the Electrical section.

Thanks,

[motornut]

aside from just getting bounced/banged
check the connections/ground,
are they the same brightness when on?
same flasher speed when turning?

[7dee2]

Motornut thanks for the quick response.

Headlight is not loose, I can clean the connections (plug), they are the same brightness when on. Flasher speed, not sure how this relates but yes flasher speed is the same from left to right or 4 ways.

A little more information is the truck seems to be a 64K mile original survivor. Electrical seems to be in very good condition except for this problem.

Thanks,

[motornut]

I had a broken ground in the headlight
drove me nuts.one was headlight dimmer and that turn flashed slower
PO had opened up the slide on plug, tried to attach it by rebending the plug copper over it
should be a pic in the thread below for 78 jimmy ,front grill etc was off for touch up