Educate me: What is the pupose of cab roof marker lights?
 

If my 72 K20 had factory cab marker lights I'd be jazzed as I like the look. Unfortunately, it doesn't. What's the purpose of these lights anyway? Do these serve a purpose other than as truck "bling"?

Re: Educate me: What is the pupose of cab roof marker lights?
 

I'm sure someone can give you a purpose for them, such as increased visibility of the truck to oncoming traffic, but what I wanted to say is to be glad you don't have them. I've heard they tend to leak , which rusts your cab roof to hell after 45 years
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Re: Educate me: What is the pupose of cab roof marker lights?
 

Never considered the rust issue - good point.

Re: Educate me: What is the pupose of cab roof marker lights?
 

Federal law requires them on vehicles greater than 80" wide along with additional red rear lights. I'm not sure why people order them on SRW pickups. Truck with snowplow greater than 80" or one that frequently carries loads greater than 80"? Maybe just the supposedly big truck "cool factor".

Re: Educate me: What is the pupose of cab roof marker lights?
 

cool factor is good enough for me, sure WISH I had a clearance light cab to go with my clearance lights! :lol:

I always just assumed that they were meant to help illuminate passing "under" something, like, oh, i don't know, a really low hanging bridge, pipe, factory, industrial type stuff... Thus the term "clearance"... But now that I think about it, that's kinda dumb. Then again, if you've ever tried to park a truck in a Washington DC parking garage...

Re: Educate me: What is the pupose of cab roof marker lights?
 

Ya it's for other vehicles to tell what's coming imagine being on a narrow two lane road and its dark as all can be and u see two headlights coming at u u switch to ur dims think everything is fine then a big old big rig bout blows u off the road cause it didn't have these marker lights to give u a hint what was coming lol same purpose. U can get aftermarket cab lights that fit the ( non cab light) trucks they don't look the same but add the cool factor non the less at night
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Re: Educate me: What is the pupose of cab roof marker lights?
 

I've had several trucks with "clearance lamps" and none have leaked. Like anything else on a vehicle,routine inspection prevents problems. The purpose is safety. They offer increased visibility of larger vehicles for oncoming traffic. Back when the general public was smarter,it let people know the vehicle approaching is bigger than them and will have a much greater stopping distance. They are also referred to as ICC lights and are part of an overall package mandated for heavy trucks. On the rear they let drivers know the vehicle ahead may be traveling slower than other traffic. The law requires any truck over 5t GVW to have them. Since dual rear C/30s fall into that bracket and GM used a special panel for them in 69-72,the lights were offered on the lighter trucks,too...mostly for bling factor and for those wanting more safety. The first truck nuts would put things on their pickups that the big trucks had and mounting cab lights was at the top (get it?) of the list of favorites. I used to notice when driving my trucks with clearance lamps at night that people would sit and wait compared to ones that didn't where they'd pull right out on you. From a distance they just see the lights and figure it's a big ole KW coming at them. There days not so much. They've degenerated to the point of not taking responsibility for their own safety and pull out anyway.

Re: Educate me: What is the pupose of cab roof marker lights?
 

Good info here - thanks guys!

Re: Educate me: What is the pupose of cab roof marker lights?
 

So, on this subject- anybody have experience adding them to a non-clearance light cab? Any thoughts on the quality of those offered by LMC and the like? Other suppliers of quality repro or period style cab lights? Is there a tutorial here somewhere on the board that I missed?

Re: Educate me: What is the pupose of cab roof marker lights?
 

any big truck store has them also. they even have the chrome west coast mirrors for our trucks.

Re: Educate me: What is the pupose of cab roof marker lights?
 

Great question... I never thought about it :metal:

Re: Educate me: What is the pupose of cab roof marker lights?
 

Mine were factory not an option attachment. They actually have a flat mounting platform formed into the roof panel to fit the fire hat style factory lights. Only one way to remove them and that's to cut the roof panel out and re-weld new one. Aftermarket are known to leak and factory will eventually if the rubber seal under the light goes unchanged. However, I have rewired for led light under the lenses and i have not one sign of moisture in between roof panels or around the holes.

Re: Educate me: What is the pupose of cab roof marker lights?
 

the ones offered by LMC are a nice setup with flexible rubble seals under the lenses. I purchased a set but could'nt use them since I had factory mounting locations on the cab.

Re: Educate me: What is the pupose of cab roof marker lights?
 

I don't really care for them

Re: Educate me: What is the pupose of cab roof marker lights?
 

They are def an acquired taste. but I get alot of comp on mine. Tried darkening one set......that made it look rediculous

Re: Educate me: What is the pupose of cab roof marker lights?
 

I can see them on Big Freightliners, thats about all honestly

Re: Educate me: What is the pupose of cab roof marker lights?
 

I have put the 69+ lights on trucks with regular roof panel. They fit fine and if you don't know these trucks inside & out you'd think they were factory. TX Fireman has a You Tube clip showing an easy way to pull the wire through the windshield post.

I suggest you don't put them on your truck...unless you have a Big Freightliner. But,they already have them

Re: Educate me: What is the pupose of cab roof marker lights?
 

Well DUH ?!, All of them have em

They look tacky

Re: Educate me: What is the pupose of cab roof marker lights?
 

actually. no, they don't (look tacky). it's an individual, and, as buckskin posted above, acquired taste. it's generally a C20/30 thing, more common on 30's, but I've even seen them on 10s as well - with the pad cab (i.e. original option). but they are far from tacky. tacky would be something like telling someone that what they are interested in is tacky. if the op had asked for opinions on what they look like, then that would be fair game. he inquired as to their purpose.

now, back to relevant posting. this is an interesting thread. my apologies for the interruption.

Re: Educate me: What is the pupose of cab roof marker lights?
 

Everyone has an Opinion Jocko

Well my mistake I had thought people put them on C-10's, and what not..Well I guess if you like it then do it, and if not don't do it

Re: Educate me: What is the pupose of cab roof marker lights?
 

and yours, sir, is irrelevant in this thread and was not asked for by the OP...... wow, seen such nonsense on other forums but never on this forum. dissapointing. I agree Jocko, interesting thread.

Re: Educate me: What is the pupose of cab roof marker lights?
 

Don't care, Still relevant with them, just an opinion

To me they look Tacky on the C-10's, but with Wreckers, and Flat beds they are fine

But from reading things, they can possibly leak over time, I guess you can put something around them to prevent this
Not really sure how to help you..I am in the Learning process :lol:


Anyway, Do whatever makes you happy man..Like everything else things have their Ups and Downs,Good Luck

Re: Educate me: What is the pupose of cab roof marker lights?
 

If you don't like the looks of cab roof marker lights that's ok but ... negative responses is not a team response. Sometimes the best response is no response. Lets post positive responses. Thanks

Re: Educate me: What is the pupose of cab roof marker lights?
 

Remember the earleir 67-68 style carried on through 72 on the Suburbans and Panel trucks. Here is a shot of Joesjunk factory lamps U01 $26.00.

Re: Educate me: What is the pupose of cab roof marker lights?
 

no kidding? I always thought those kind of lights were aftermarket! I had no idea they were 67-68 factory lights. That clears a lot of things up for me - didn't realize. Thx Tim.