Cab Light Mount Questions

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Doppleganger

Full Access Member
Joined
May 24, 2019
Posts
12,424
Reaction score
57,454
Location
OH-MI: Just like it sounds
First Name
Chris
Truck Year
1985
Truck Model
K20
Engine Size
5.7
A couple of basic questions about adding cab lights - devil's in the details as they say.

Got these mounts:
You must be registered for see images attach

One on the left is a GM original. One on the right (hardware store) is the same thread and size (trunk is a tad thicker) - but rubber instead. I like the rubber one but it would require a larger hole to be drilled. How does the stock metal GM one mount? (not 100% sure how the rubber one installs either). Does it expand like a rivet? Looks similar to those anchors they use for the door mirrors. I could dab it with panel adhesive if need be. Dunno.

Nuther question: what size /color bulbs do you guys use? Going LED of course - the 168 is slightly brighter than a 194. Also need to find a GOOD LED bulb - most everything is chicom - just need to find a better brand.

I mocked one up and was kind of meh on the output of the clear bulb with amber lense. No idea what an amber bulb would be like.

Just thinking out loud before holes get drilled.....

THX
 

Blue Ox

Turning Diesel Fuel Into Fun
Joined
Mar 27, 2018
Posts
5,132
Reaction score
11,679
Location
LI-NY
First Name
Derek
Truck Year
MCMLXXXV
Truck Model
K20HD
Engine Size
6.2L
The factory lights are screwed into nuts that are welded into the sheet metal. The bulb socket is held by the lens gasket.

When I retrofitted them to the Suburban I used Nutserts. They're machine screws, not sheet metal screws.
 

Doppleganger

Full Access Member
Joined
May 24, 2019
Posts
12,424
Reaction score
57,454
Location
OH-MI: Just like it sounds
First Name
Chris
Truck Year
1985
Truck Model
K20
Engine Size
5.7
The factory lights are screwed into nuts that are welded into the sheet metal. The bulb socket is held by the lens gasket.

When I retrofitted them to the Suburban I used Nutserts. They're machine screws, not sheet metal screws.
I wonder if nutserts could be used for the door mirrors also? I realize I digress but that will be a future issue. This truck is like death by a thousand cuts to me. lol
 

fast 99

Full Access Member
Joined
Dec 31, 2021
Posts
1,885
Reaction score
2,677
Location
Spokane, Washington
First Name
Brian
Truck Year
81,85
Truck Model
K20
Engine Size
350
I wonder if nutserts could be used for the door mirrors also? I realize I digress but that will be a future issue. This truck is like death by a thousand cuts to me. lol
Yes, low mount mirrors also have an internal reinforcement.
 

Blue Ox

Turning Diesel Fuel Into Fun
Joined
Mar 27, 2018
Posts
5,132
Reaction score
11,679
Location
LI-NY
First Name
Derek
Truck Year
MCMLXXXV
Truck Model
K20HD
Engine Size
6.2L
I wonder if nutserts could be used for the door mirrors also? I realize I digress but that will be a future issue. This truck is like death by a thousand cuts to me. lol

Yes, low mount mirrors also have an internal reinforcement.

Just from cr@ppy memory I think the mirror screwed into plastic inserts, but you'll definitely need that internal brace.
 

Doppleganger

Full Access Member
Joined
May 24, 2019
Posts
12,424
Reaction score
57,454
Location
OH-MI: Just like it sounds
First Name
Chris
Truck Year
1985
Truck Model
K20
Engine Size
5.7
I think these anchors need drilled out? The bottom one IIRC is the one with the steel brace. Seems this has been covered but I dont remember where.

You must be registered for see images attach
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
29,938
Reaction score
26,792
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
That original GM piece looks to just be a nutsert. It's been many years since I had the cab lights off of my '79, but I don't remember it having the special stamped roof skin with nuts pressed and welded to the skin for the lights, like on the later models. If I pulled a lense off to refresh my memory, I'll bet I find nutserts.
 

Doppleganger

Full Access Member
Joined
May 24, 2019
Posts
12,424
Reaction score
57,454
Location
OH-MI: Just like it sounds
First Name
Chris
Truck Year
1985
Truck Model
K20
Engine Size
5.7
That original GM piece looks to just be a nutsert. It's been many years since I had the cab lights off of my '79, but I don't remember it having the special stamped roof skin with nuts pressed and welded to the skin for the lights, like on the later models. If I pulled a lense off to refresh my memory, I'll bet I find nutserts.
I found them called 'well nuts' and they apparently bulge when you thread a screw into them....like the cheesy wall anchors in drywall. Will probably use those since thats what comes with the GM kits.

Now to find whatever that door mirror uses. :hat:
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
29,938
Reaction score
26,792
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
I found them called 'well nuts' and they apparently bulge when you thread a screw into them....like the cheesy wall anchors in drywall. Will probably use those since thats what comes with the GM kits.

Now to find whatever that door mirror uses. :hat:

Yeah, well nuts is another name. They take more force than that to install though. They install like a big rivet. The use of a rivnut install tool is by far the best way to install them, but you can do the same thing (carefully) with a long bolt and a stack of washers. There are several types of install tools, some cheap and some that are more expensive.

If just using a bolt and washers, I'd recommend against the GM ones. I'd get some commonly available rivnuts that have a serrated shell, to prevent them from spinning during the install.
 

SquareRoot

Full Access Member
Joined
Mar 18, 2017
Posts
4,048
Reaction score
7,642
Location
Arizona
First Name
Mike
Truck Year
85
Truck Model
K20
Engine Size
350
I splurged and bought a nutsert kit. Has the tool, various aluminum and steel nutserts. I put that S**T on everything! Best thing I ever bought. Except for maybe the weather pack connector kit.
 

Blue Ox

Turning Diesel Fuel Into Fun
Joined
Mar 27, 2018
Posts
5,132
Reaction score
11,679
Location
LI-NY
First Name
Derek
Truck Year
MCMLXXXV
Truck Model
K20HD
Engine Size
6.2L
That original GM piece looks to just be a nutsert. It's been many years since I had the cab lights off of my '79, but I don't remember it having the special stamped roof skin with nuts pressed and welded to the skin for the lights, like on the later models. If I pulled a lense off to refresh my memory, I'll bet I find nutserts.

My cab definitely has factory clearance lights and there is a D shaped depression stamped into the sheet metal with a square nut welded or brazed into it. Not saying they're all like that, but mine is not a Rivnut or Nutsert, it's part of the roof. There may have been a change made in the '81 refresh, so your '79's configuration may be an earlier version.
 

bucket

Super Moderator
Staff member
Super Moderator
Joined
Aug 3, 2010
Posts
29,938
Reaction score
26,792
Location
Usually not in Ohio
First Name
Andy
Truck Year
'77, '78, '79, '84, '88
Truck Model
K5 thru K30
Engine Size
350-454
My cab definitely has factory clearance lights and there is a D shaped depression stamped into the sheet metal with a square nut welded or brazed into it. Not saying they're all like that, but mine is not a Rivnut or Nutsert, it's part of the roof. There may have been a change made in the '81 refresh, so your '79's configuration may be an earlier version.

Yeah, that's what I was trying to get at, that there was a design change at some point and the earlier trucks didn't get a dedicated roof stamping for the cab lights.

For the trucks anyway. Does anyone know if the Suburbans wound up with a dedicated roof stamping as well? So few of them (comparatively) were ordered with cab lights, that would be an expensive manufacturing change, I'm guessing. Large roof and low production.

I never removed the lights from my '90 Burb to know what was under them. They were indeed factory installed though.
 

Doppleganger

Full Access Member
Joined
May 24, 2019
Posts
12,424
Reaction score
57,454
Location
OH-MI: Just like it sounds
First Name
Chris
Truck Year
1985
Truck Model
K20
Engine Size
5.7
I splurged and bought a nutsert kit. Has the tool, various aluminum and steel nutserts. I put that S**T on everything! Best thing I ever bought. Except for maybe the weather pack connector kit.
Which one did you get and how does it differ from a pop riveter?
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
6,599
Reaction score
11,385
Location
Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
You’re overthinking it….get some riv nuts, nut serts, blind nuts, whatever and pop them in. It’s holding a teeny tiny light with 3 screws. It will hold longer than you’ll be driving the truck.
 

SquareRoot

Full Access Member
Joined
Mar 18, 2017
Posts
4,048
Reaction score
7,642
Location
Arizona
First Name
Mike
Truck Year
85
Truck Model
K20
Engine Size
350
@Doppleganger
It has different size "rods" depending on the size of nutsert you're using
 

Attachments

  • IMG_20240908_095450523_HDR.jpg
    IMG_20240908_095450523_HDR.jpg
    309.9 KB · Views: 12
  • IMG_20240908_095504905.jpg
    IMG_20240908_095504905.jpg
    168 KB · Views: 15

Forum statistics

Threads
43,515
Posts
937,074
Members
35,397
Latest member
sqrbdy
Top