GMC headlights
 

Ok, dumb question but how are the headlights configured on a GMC? Are all the bulbs the same and the inner pair just aimed higher for the high beams? I thought there was only one style of T3? Are only 2 on at a time when on high or low?

Re: GMC headlights
 

outers are low/high inners are high only.
when on in low beam, only the outers are on
when on in hight beam, all 4 are on.
T3 made both the inner and outer, plus the larger 7 inch bulbs too

Re: GMC headlights
 

Thanks Andy, so all four bulbs are the same?

Re: GMC headlights
 

No. He said the outers are hi/lo beam and the inners are hi-only...inner= single element and outer = double element. T-3 was a series of bulb made by Wagner,I believe. I'd have to check. Haven't thought about it for a while. T-3s are like Super Blues or other series made by the same company.

Re: GMC headlights
 

Just looked at my 2 GMC's and it looks like the inners are marked with a "1" and the outers are marked with a "2". I also just learned the headlight bezel is a little different between a 69 and a 67 in that the 69 has reliefs for the screwdriver so the bezel can stay while the headlights are worked on

Re: GMC headlights
 

I think you will find a double plug on one headlight, and a triple on the other. And you are correct, 67 didn't have any notches to aim the headlights in the bezel. Most 68s did, but not all.

Re: GMC headlights
 

The headlights are 2 different part numbers at the parts store too.

Re: GMC headlights
 

Yep, I noticed that after I got them out. Good news, I've got 3 T3's for the 67.

Re: GMC headlights
 

http://www.sylvania.com/ConsumerProd...RG-Results.htm here is part #s that are the new replacement #


High beam headlamp
H5001

Low beam headlamp
H5006

Re: GMC headlights
 

they make repro T3 lamps now... so don't spend too much time looking for 40 year old lamps.