[Dick Boneske]

When the headlights only are on, all three bulbs in each tail lamp should be the same brightness. When the brakes or directionals are on, the outside two of the three are brighter. If the center bulb is brighter than the outside two, you have the wrong bulb in the center position. It should be a single filament bulb #1156. This would match the outside dual filament bulbs #1157. The original bulbs for the '64 GTO were #1037 for the dual filament and #1056 for the single filament. There is a newer dual filamant bulb #2057 which will work, also, but may be brighter than the 1157 which is widely available.