What TLL9RK Actually Is
TLL9RK is a left-hand stop, turn, and tail lamp built for trailer service. All three functions live in one sealed housing, so you run one lamp instead of stacking separate stop and turn units. It carries an integrated reflex reflector, which covers the reflector requirement in the same footprint and keeps the rear of the trailer legal without a bolt-on reflector strip.
The housing is submersible and IP67 sealed. That matters on boat trailers, where the lamp goes underwater every launch, and on any trailer that lives in road spray, salt, or gets pressure-washed weekly. Water intrusion is what kills most trailer lamps, and a sealed lens-to-housing joint is the whole point of this design.
Internally it's solid-state LED. No filament to shatter on washboard gravel or a rutted launch ramp. Rated 12V, sized for trailers under 80 inches wide, and mounts in the industry-standard 4-inch round or 6-inch oval pocket, so it drops into existing trailer light openings without cutting new holes.
Why These Numbers Cross
TLL9RK, TL38RB, and STL39RB describe the same functional lamp: a left-side, 12V, submersible stop/turn/tail assembly with integrated reflector, built to the standard round or oval trailer light pocket. Trailer lighting is one of the more standardized corners of the industry because the mounting cutouts, the grommet sizes, and the lighting code requirements are fixed. That's why numbers from different catalogs land on the same physical part.
TL38RB and STL39RB are Optronics numbers. They're listed here for identification only so you can match what's stamped on the back of your old lamp or printed on the packaging in the parts room. PartStop is not affiliated with, endorsed by, or authorized by Optronics or any other manufacturer.
Where these numbers can diverge is in the small stuff: pigtail versus hardwire tail, connector style, and whether the kit ships with a grommet or mounting bracket. Check what your trailer uses before you order. If your old lamp mounts on a bracket and the replacement expects a grommet pocket, you'll want to know that on the bench, not at the ramp.
Check Before You Order
Confirm the side. This is the left-hand lamp. Left and right units are not always interchangeable on stop/turn/tail assemblies because of license plate illumination windows and wire lead routing. Flip your old lamp over and read the number cast into the back before you commit. If the casting is unreadable from corrosion, measure the cutout and note whether it's a 4-inch round or 6-inch oval opening.
Then check the electrical side. Verify 12V, confirm your trailer is under 80 inches wide, and inspect the ground. Most "bad light" calls are a corroded ground stud or a chewed-up harness, not the lamp. A cross-reference is a starting point, not a fitment guarantee — confirm by VIN or by the number on the part you pulled off.
TLL9RK Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to TLL9RK. Use them to identify the part — then confirm the exact fit by VIN or the number stamped on your old unit before you order. An interchange is a starting point, not a fitment guarantee.
| Brand / Line | Cross-Reference Numbers |
|---|---|
| Optronics | TL38RB, STL39RB |
Frequently asked questions
Is TLL9RK the same as Optronics TL38RB or STL39RB?
They cross as the same functional part: a left-side 12V submersible stop/turn/tail lamp with integrated reflector for standard trailer light pockets. Those Optronics numbers are listed for identification only. Verify against the number on your old lamp or your trailer documentation before ordering, since connector and mounting details can vary between catalog listings.
Will this survive being dunked at a boat ramp?
That's what it's built for. The housing is submersible and IP67 sealed, designed for wheel-well immersion service on boat trailers. Solid-state LED construction also means there's no hot filament to crack when cold water hits it. Just make sure your ground connection is clean and sealed too, because a corroded ground will take out a good lamp.
Can I use this lamp on a wide trailer over 80 inches?
No. This unit is rated for trailers under 80 inches wide. Trailers 80 inches and wider fall under different lighting requirements and need lamps rated for that application. Measure your trailer at its widest point before ordering, and if you're on the line, go by the manufacturer's stated width, not a tape measure across the fenders.
Not sure it fits? We check before you pay.
Run your VIN and we’ll match parts to your exact truck, or call the counter — a person who knows trucks verifies fitment by OEM number before the order ships. No wrong-box returns.
More cross-reference guides
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Every part below is a Premium Quality aftermarket Direct Replacement with published OEM cross-reference numbers, a 6+ month warranty and same-business-day shipping from Tacoma, WA. Not sure it fits? Run your VIN — or call and a person who knows trucks will verify fitment before you pay.