1971 GMC Step side unknown plug below tailgate
 

Hey everyone, I have a 1971 GMC 1Ton step side and have been doing front to back wiring replacement with an AAW kit. The truck has never had license plate lights as long as I've owned it and my grandpa who gifted it to me seems to remember it never having one either (owned it since the early 80s) I saw this odd looking plug on the rear just below the tailgate and I think at one point in time it was the plate light but I'm just not sure. Does have one wire running to it from underneath the truck but the original wiring is such a mess it's hard to tell what it is. Just wondering what type of plate light bracket it would've had and wanted to share a pretty odd truck. It's a 1 ton step side with the 9ft bed, 4 speed.

Re: 1971 GMC Step side unknown plug below tailgate
 

Check out post 26426 here ....https://67-72chevytrucks.com/vboard/...11054....might answer your question as this truck has a similar application

Re: 1971 GMC Step side unknown plug below tailgate
 

It seems like it's a cut portion of a "Guide It" License plate bracket" like this: https://www.ebay.com/itm/394241773970

The main rear plug should have 4 brown wires, (2) marker lights, (2) tail lights. There should be a splice from the left tail light for the license plate light, but you could get it from any brown wire.

Re: 1971 GMC Step side unknown plug below tailgate
 

Thanks for the info I'll look into some way of getting that bracket to work. I wonder if that was original to the truck or not since the color seems to be the same and similarly worn paint wise

Re: 1971 GMC Step side unknown plug below tailgate
 

Looking more closely at your truck, it seems that there is interference with the tailgate. Like the first time the tailgate was lowered, it crushed the housing, glass, and bulb. The "standard" was a white front bumper with no rear bumper. I'm not sure if these license plate brackets were factory or dealer installed. In your case, I would find some other light housing or maybe even a pair that you can mount on the bumper and either side of the license plate.

Re: 1971 GMC Step side unknown plug below tailgate
 

The first two pics are of what the original part looked like. Yours is missing some parts. At least the bulb, glass lens, metal lens holder and screws and possibly the bulb receptacle.

Third pic is what it looks like once it cut down and mounted.

Fourth and fifth pics are of the way it was used with a license plate.

Re: 1971 GMC Step side unknown plug below tailgate
 

These brackets were originally used as rear license plate brackets on trucks with no rear bumper. Back then these trucks were not required to have a rear bumper from the factory. Step bumpers were added by dealerships (to promote their dealership), sold by aftermarket companies, and offered as a factory option (this option would be listed on the SPID). Seems like the factory option bumper is really rare.

Here's a pic of what the unmodified mount looks like mounted in the proper location for a truck with no rear bumper. However, someone mounted a bumper in from of the mount without removing it.

Re: 1971 GMC Step side unknown plug below tailgate
 

Those blue truck pics look awfully familiar LOL
That light didn't work when I got the truck, replace all the connectors and everything's fine now.

Re: 1971 GMC Step side unknown plug below tailgate
 

LOL! I went on a deep dive a while back trying to figure out where these little license plate light brackets came from and I collected a ton of pics during my research. I think those pics came from BAT or some other site that uses webp files. I had to convert them to jpg post them here.

Re: 1971 GMC Step side unknown plug below tailgate
 

thats kinda what i was thinking too. it never really bothered me until i was doing the wiring and figured i should get some kind of light working for the plate. it looks like it was mounted in the perfect spot to get smashed the second anyone dropped the tailgate while connecting the chains

Re: 1971 GMC Step side unknown plug below tailgate
 

You've got an unusual pickup, thee.
You should tell your story of it, here. 9 foot bed is pretty unusual, I read, here.

Re: 1971 GMC Step side unknown plug below tailgate
 

I just put up a post about the history a few min ago if you'd like to check it out
Thanks!