Detail Picture Request - 69 U26 Underhood Lamp

[ZLP955]

I searched here and over at TC but couldn't find an answer.
I'm looking for detailed pictures of a known original 1969 RPO U26 underhood lamp (assembly 3916764 as per AIM U26 A1). I'm specifically interested in the housing dimensions, if the back of the reflector is solid or has a hole in it, and if the 2 mounting holes are both round, slotted, or one of each. As the lamp should attach to the existing holes in the hood, I suspect the holes in the lamp wouldn't need the tolerance of slots, but you never know.
Any help would be much appreciated, there are many different styles available out there, each similar but subtly different and (of course) everyone insists the one they're selling is 100% correct.....

[ZLP955]

Can anyone help?

[ko-lek-tor]

Ask and it will be given I will get dimensions later & post.

[ko-lek-tor]

I tried.

[cook_dw]

Holy crap...  Soak that dude in some Evaporust!!  lol

[ko-lek-tor]

I said I had one, I did not say it was pristine. I do not have time to clean it as the wife has me doing a bunch of honey-do's for T-giving prep,ugh! Oh, and that is pristine for Ohio BTW. lol

[69 Zee]

Bentley, you didn't drag that up from the Ohio River did ya ? ..lol   

But thanks for the detailed info though.

[69pace]

Holes were pre drilled in the flat hoods, ZL2 Page 418 of the AIM shows that you had to use the lamp as the template and drill them on the line.

The GM service replacements had slotted holes because it was a best of bread part and meant to replace several different lamp housings across lines and divisions.

The hole in the shield was for heat escape, one supplier had them one did not. The originals came from two suppliers. Hobbs a division of Stewart Warner (these were on a ton of Chevelles and Novas) were the units without the heat escape hole. I do not remember off the top of my head who the second was.

The reproductions out there are not exact but are fairly close. I seem to remember the bottom tang is a square 2 inches by 2 inches on the warner's built ones 1 and 3/4 ish on the other. Jeff "Pace Car Jeff" on eBay has tons of these on sale all the time and usually has measurements.

On last note on the older ones. Some of them used a mercury bulb switch capsule. With age the bulb which was steel or glass can shatter and the mercury can leak. Its deadly. Most used and all the reproductions use a steel bb to complete the circuit when tipped in the right direction. You can tell the difference by the sound. If it is silent and you meter reads the circuit closed its mercury. If you hear the bb moving back and forth no health issues.

[ZLP955]

Thanks Bentley, that is awesome detail, exactly what I was looking for. Nice patina too!
Brian, thanks for all that info, much appreciated. Interesting point about the dangers of the original mercury bulb switch; I guess that would likely be a hazard considering I would have to get it shipped to me by air, so am I correct in thinking the type that takes a standard bulb (therefore having the integral switch, not within the bulb) would be safer?

[bcmiller]

Correct. Anytime you can avoid dealing with mercury is a good day. Nasty stuff...

[69pace]

As said the majority of the reproductions and some original used the bb's. Mercury began to be phased out of production in the 70's when the full danger of neurological impairment was understood although there had been centuries of suspicions since all pressed or formed felt Hatters in the hat trade went mad hence the term "Mad as a hatter".  Around this time the warnings about eating Tuna fish surfaced and continue to this day. Did you know the average person height and weight should not eat more that one can or packet of tuna a month? Pregnant women shouldn't eat it at all.

There are new "mercury" style switches and contact bulbs where a conducting liquid is replacing the mercury in the capsule bulb.

The term bulb capsule is a self contained unit that was in the base of the map assembly and has nothing to do with the actual light bulb. Several types of electrical switches used this bulb capsules either glass or steel. More older homes have a glass capsule bulb filled with mercury in their round Honnywell home heating/cooling thermostat. 

[ZLP955]

Brian do you know if it's possible to retrofit a bb switch and bulb into an original housing?

[ko-lek-tor]

As said the majority of the reproductions and some original used the bb's. Mercury began to be phased out of production in the 70's when the full danger of neurological impairment was understood although there had been centuries of suspicions since all pressed or formed felt Hatters in the hat trade went mad hence the term "Mad as a hatter".  Around this time the warnings about eating Tuna fish surfaced and continue to this day. Did you know the average person height and weight should not eat more that one can or packet of tuna a month? Pregnant women shouldn't eat it at all.
There are new "mercury" style switches and contact bulbs where a conducting liquid is replacing the mercury in the capsule bulb.

The term bulb capsule is a self contained unit that was in the base of the map assembly and has nothing to do with the actual light bulb. Several types of electrical switches used this bulb capsules either glass or steel. More older homes have a glass capsule bulb filled with mercury in their round Honnywell home heating/cooling thermostat. 

I am sure if I Google this, I could learn for myself , but in wanting all here to benefit, I ask this:
The Mercury dangers are only if ingested or absorbed through the skin, I am led to believe? Mercury contained in a capillary tube poses no health danger unless the tube is damaged allowing the Mercury to escape?

[69pace]

Yes you are correct the bulb capsule - glass or steel - has to be broken or breached to open and let the mercury escape, if it has then contact with the outer housing if contaminated may contain enough to be harmful especially if your lifetime cumulative count is already high. The unit in general good condition shouldn't pose any danger to most people. BTW The trunk lights are based on the same system switch capsules.

I guess you could rebuild a mercury switch unit with the guts of a bb unit but why risk releasing the contents in the process, then the State and or Federal EPA has to get involved and clean it up as a hazmat site.

If I had a mercury based under hood unit I would carefully package the original unit in a sealed container like a glad-ware sandwich box, then bag it in a zip lock, mark toxic - mercury and then store it someplace safe and out of kids reach if keeping original parts is important to you.

Then I would hang one of the decent replacements on your hood. The one Ricks sells is the correct size and shape (2x2 hanger) and uses a bb switch. Even replace the other style with the shorter hanger and the hole for heat escape with the standard 2x2. You can't see the hole when the bulb is installed and if it bothers you then drill a hole in it. The fact your vehicle got one or the other style was luck of the draw at the assembly time, which suppliers train came in on time. No one will notice or care IMHO unless you have a trailer queen for judging and where is the fun in that?