Delco/Guide Headlight Part Number History?

[Donald Brunswick]

I'm trying to do some research on four headlight system bulbs.
Does anyone have the Delco/Guide part numbers (ie 4000 low beam)for the lifecycle of the four headlight system? I would like to know the Delco/Guide part numbers for the high beam and low beam lights and what year span they covered. Lettering on the face of the bulb. I have some pretty good information on bulbs up to 72, not part numbers, but nothing past 72. Any help would be appreciated.

donald

[Joe L.]

Re: Delco/Guide Headlight Part Number History?

Donald------

I can give you the part numbers but it's not going to be a lot of help in defining the differences in the sealed beam units over the years. It's very possible, and even likley, that there were some differences WITHIN a given part number over the years of its use. But, here they are:

1958 through 1963

inner---GM #5948501

outer---GM #5948502

1964 through 1972

inner---GM #5956001

outer---GM #5956002

1973 through 1978

inner---GM #5965416

outer---GM #5964600

1978 through 1982

inner---GM #5930632

outer---GM #5964600

A few other things: it's VERY possible that sealed beams manufactured by entities other than Guide were used in PRODUCTION or SERVICE under the above numbers. I doubt that much of this occurred before about 1973 but it's very possible after about 1973.

Also, the above year ranges are a GENERAL guide to application of the part numbers listed. For items like this it's VERY possible that there was overlap, and perhaps considerable overlap, at the beginning/end of model years.

[Michael H.]

Re: Delco/Guide Headlight Part Number History?

Donald,

I have some information for your research project on headlamp bulbs. The change in part number from 1963 to 1964 was due to a major change in the entire electrical system on all Chevrolet's and Corvette's for the new 64 model year. The paragraph below is word for word from some old GM paperwork that I have and it describes these changes;

"ALL HEADLAMPS AND BULBS USED FOR ANY LOCATION IN ALL 1964 CHEVROLET AND CORVETTE VEHICLES WILL BE OF A NEW HEAVY FILIMENT TYPE FOR INCREASED DURABILITY. EACH BULB UNIT WILL BE IDENTIFIED WITH THE STANDARD TRADE NUMBER STAMPED ON THE BASE. FOR THE SERVICE REPLACEMENT OF ANY BULB USED ON A 1964 VEHICLE, CARE MUST BE EXERCISED TO SELECT THE PROPER RATED BULBFOR THIS PURPOSE. IF A SIMILAR BULB FOR A PREVIOUS MODEL WERE INCLUDED IN A 1964 SYSTEM, NO MAJOR DAMAGE WOULD OCCUR BUT THERE WOULD BE A DEFINITE DIFFERENCE IN LIGHTING BRILLIANCE OFFERED BY THESE BULBS. THE USE OF THE 1964 BULBS ON PREVIOUS MODELS IS NOT RECOMMENDED DUE TO THE INCREASED AMPERAGE REQUIRED FOR THESE UNITS. 1964 ELECTRICAL SYSTEMS ARE CALIBRATED AND REVISED SPECIFICALLY TO MEET THESE REQUIREMENTS"

This is the only thing I have ever seen on paper from GM or Delco about this change. It also would explain the part number and physical design change of all of the wiring harnesses from 63 to 64. The new 1157 tail/stop lamp bulbs would have been part of this change also, replacing the 1034 from previous years.

I don't know if the actual physical appearance of the new 1964 headlamp bulb was different than the 1963. I've compared the two but never noticed a difference.

Michael