If your vehicle came from the factory with 4×6 sealed beam headlight housings, you already know that upgrading to an LED type housing is one of the best ways to improve the style, safety, and performance of your lighting. We pulled together the most popular 4×6 LED headlights on the market and tested them one by one, and in this review we are focusing on the Truck-Lite 4×6 LED headlight. It is not the most expensive option on the table, but after our testing it stands out as one of the best quality and brightest units we measured.
Who Makes the Truck-Lite 4×6 LED Headlight?
Back when automotive LED headlights were brand new, Truck-Lite was the company that created the first 7 inch round sealed beam LED headlight. That is a serious piece of lighting history. Today they have taken that experience and applied it to a brand new 4×6 LED headlight, and the result is genuinely impressive. If you want to see how it stacks up against everything else we tested, take a look at our roundup of 4×6 rectangular sealed beam headlight housings and our broader full lineup of sealed beam headlight upgrades.
Will It Fit Your Vehicle? Sealed Beam Part Numbers
Some common 4×6 sealed beam headlight part numbers are 1A1, 2A1, 4656, and 5001. If your original sealed beam headlights match any of those part numbers, the Truck-Lite 4×6 LED headlight is a great direct replacement. That is the beauty of the 4×6 format, since the housings drop straight into the same brackets and use the same style connectors your vehicle already has.
The Blackout Design Explained
This is an interesting design because it is not technically a black housing, but it looks black. The top section of the headlight houses a heatsink, a driver, and an LED. The LED shines down into the reflector, and the beam pattern is cast out from the reflector surfaces. Each of the different reflector shapes helps position and create the beam pattern in a specific way.
The reason you get that really cool blackout effect is because the reflector is chrome, like a mirror. When you look up inside the housing, the circuit board is black. So the chrome reflector is reflecting the black circuit board back at you, which gives the headlight a stealthy, dark appearance while still functioning as a proper mirror-like reflector. It is a clever trick that keeps the optical performance intact while looking a lot more modern than a typical chrome reflector.
Low Beam vs High Beam: Part Numbers and How to Tell Them Apart
The Truck-Lite 4×6 comes in a single beam low beam, part number 27640C, and a single beam high beam, part number 27645C. When you look at them side by side, the low beam and high beam housings look almost identical, so it is worth knowing how to tell them apart before you install them.
The biggest distinction on the front is the shape of the bottom of the lens and the shape of the center section of the reflector. The low beam has two square notches on the bottom, and its center section has more reflective surfaces broken into smaller pieces. The high beam is notched a couple of times on either side of the reflector bowl, and its center section is more clear, using one big reflector rather than several separate reflective segments.
Flip them around to the back and there is one more easy tell. The low beam has three wires coming out the back, while the high beam only has two. This is because on a lot of vehicles the low beam is on the outside and stays on when you switch to high beam. So whether you are energizing the single low beam circuit or the single high beam circuit, your outside headlights will always be on, and the only thing that changes is your high beam flipping on when you go to high. Behind the heatsink up top you get the wires feeding into a really nice waterproof connector, and a moisture vent right next to it. It is simple, it fits, and it works.
How We Test: Lumens vs Lux
To compare each headlight fairly, we set them up 25 feet away from a wall and used our digital lux meter to measure light at every point of the beam pattern. People always ask why they never hear about lux, and the honest answer is that to get the whole picture you need three things: the shape of the beam pattern (is it a good, usable pattern), the lumen output of the LED (is it making a lot of light), and how those two things work together to create usable light in front of the vehicle. That last part is why we measure lux.
Keep in mind this is semi-scientific. We measure every single point of the beam pattern, then report the single brightest point as our benchmark for each headlight. That gives us a consistent number to compare across every 4×6 LED headlight we test.
Stock Sealed Beam: The Baseline
If your vehicle comes with sealed beam headlights, here is what you are starting with. The stock beam is not very wide, it has no sharp cutoff line, and the light color is a dingy yellow that just does not do you any favors at night.
We measured the stock low beam at only 650 lux at 25 feet. Then we switched to high beam and it did not really get any brighter. We measured it again at 650 lux at 25 feet, and the beam pattern just shifted up slightly. That tells you the factory sealed beam is not giving you meaningful extra reach on high beam, which is exactly why an LED upgrade makes such a difference.
Truck-Lite 4×6 LED Test Results
Low Beam (Part Number 27640C)
The Truck-Lite low beam, part number 27640C, has a raw lumen output of 850 lumens. Effective lumen output is unspecified by the manufacturer, but our measured numbers tell the real story. We recorded a maximum lux of 1140 lux at 25 feet, which is a big jump over the 650 lux stock baseline. It is DOT approved, made in the USA, backed by a three year warranty, and draws only 1.5 amps of power at 12 volts DC. It is available in black housings only.
High Beam (Part Number 27645C)
The Truck-Lite high beam, part number 27645C, is rated at 850 lumens per lamp with unspecified effective lumen output. We measured a maximum lux of 2080 lux per lamp at 25 feet, which is a massive improvement over the stock 650 lux high beam. It is DOT approved, made in the USA, backed by a three year warranty, and draws 1.2 amps at 12 volts DC. Like the low beam, it is available in black only.
Remember there is more to picking out a headlight than just the lumen rating on the box. The beam pattern shape and the lux measurement together are what determine how much usable light you actually see on the road. The Truck-Lite scores well across all three of those metrics in our testing.
How It Compares to Other 4×6 LED Options
The Truck-Lite is a reflector style headlight, which is one of the most popular formats in this size. If you are cross shopping, another strong choice is a projector Bi-LED, like the Morimoto Sealed4 Bi-LED 4×6 housing. You can also grab the Sealed4 housing direct from Morimoto or pick up the 4×6 Bi-LED housing at The Retrofit Source if you prefer to shop those retailers. And if you want another point of reference on brightness in this exact size class, check out our JW Speaker 8800 4×6 LED brightness test. To get a full feel for what matters, watch all of our 4×6 LED headlight videos and compare the beam pattern, lumen, and lux numbers yourself.
Our Final Take
After testing the Truck-Lite 4×6 LED headlight against the stock sealed beam, the improvement is not subtle. You are going from a dim 650 lux yellow beam with no cutoff to 1140 lux on low and 2080 lux on high, all while pulling very little current (1.5 amps on low, 1.2 amps on high at 12 volts DC). Add in the DOT approval, USA manufacturing, three year warranty, and that clever blackout reflector look, and it is easy to see why we rank the Truck-Lite among the best 4×6 LED headlights we have tested.
Frequently Asked Questions
What sealed beam part numbers does the Truck-Lite 4×6 LED headlight replace?
It is a direct replacement for original 4×6 sealed beam housings with part numbers 1A1, 2A1, 4656, and 5001.
What are the part numbers for the Truck-Lite 4×6 LED low beam and high beam?
The single beam low beam is part number 27640C and the single beam high beam is part number 27645C.
How do you tell the low beam and high beam housings apart?
The low beam lens has two square notches on the bottom with a more segmented reflector center, while the high beam has notches on either side and a clearer, single-piece reflector bowl. The low beam also has three wires out the back versus two on the high beam.
How bright is the Truck-Lite 4×6 LED headlight compared to a stock sealed beam?
The stock sealed beam measured 650 lux on both low and high beam at 25 feet, while the Truck-Lite low beam measured 1140 lux and the high beam measured 2080 lux at 25 feet.
Is the Truck-Lite 4×6 LED headlight DOT approved?
Yes, both the low beam and high beam versions are DOT approved, made in the USA, and backed by a three year warranty.
Meet the Experts Behind Headlight Revolution
Chris Nelson – Founder
Before founding Headlight Revolution in 2011, Chris worked as an automotive install technician specializing in lighting, sound systems, and engine performance parts. He has personally tested thousands of lighting products and works directly with lighting engineers to evaluate the technical performance behind every recommendation.
Josh Beberg – Content Production Manager
Josh leads hands-on testing and content production at Headlight Revolution. From beam pattern comparisons to real-world installations, he works directly with lighting engineers to ensure every review is grounded in measured results, not marketing specs.
