What 33700 Actually Is
This is the mounting piece for a 3/4" round lamp — the part that carries the light body and holds it square to the panel or bracket. It is not the lamp itself and not the pigtail. If your lamp lens is cracked or the diode is dead, the mount is not your fix. If the lamp moves when you push on it, this is.
The 3/4" size refers to the lamp body diameter it accepts, not the hole you drill or the bracket thickness. Measure the old lamp body before ordering. A 3/4" lamp in a 1" mount will walk around, chew the wiring at the back, and eventually short to the trailer frame.
Placement is flexible. The same mount is used at front corners, rear panels, and both sides of the trailer for clearance and side marker duty. That's why one number covers so many trailer configurations and why it shows up across multiple builders' parts lists.
Why 33700 And A11GB Cross
33700 and Optronics A11GB describe the same physical mounting for a 3/4" round lamp. The interface that matters is the lamp seat diameter and the way the mount retains the lamp body — get those two right and the lamp seats the same regardless of which number is stamped on the packaging.
Trailer lighting hardware standardised around a handful of lamp diameters decades ago, which is why interchange lists in this category run long. Different suppliers assigned their own numbers to functionally identical mounts. The Optronics number is listed here for identification only — we are an aftermarket supplier and not affiliated with or authorised by any manufacturer.
Treat the cross as a starting point, not a guarantee. Pull the old mount, check the lamp body diameter, and check how the assembly is retained in the panel — grommet-style, bracket-mounted, or through-hole. Confirm against the number on the part you removed or against your trailer VIN before you commit.
Failure Signs And Install Checks
Mounts fail from vibration and weather, not from electrical load. Highway miles work the lamp loose, the seat elongates, and the lamp starts to rock. Rocking pulls on the terminals behind it, and you end up chasing an intermittent marker light that passes a shake test in the shop and drops out at 60 mph. Replace the mount, not just the bulb.
Before you install, clean the panel opening. Rust scale and old sealant keep the mount from seating flat, which is what caused the rattle in the first place. Check the wiring behind the lamp for chafe damage while you have access — if the lamp has been loose for a while, the harness usually has a worn spot at the entry point.
33700 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 33700. 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 | A11GB |
Frequently asked questions
Does 33700 include the lamp or just the mount?
33700 is the mounting only. You supply the 3/4" round lamp and the wiring. If your lamp is also damaged, order it separately and confirm the body diameter matches 3/4" before installing.
Will this fit my trailer if my old part number doesn't match either number listed?
Possibly, but don't assume it. Interchange lists in trailer lighting are incomplete because so many suppliers use their own numbering. Measure the lamp body diameter and check the retention style on the part you removed, then compare against your trailer VIN or build sheet before ordering.
My marker light flickers over bumps — is the mount the problem?
Often, yes. A worn mount lets the lamp rock, and that movement stresses the terminals behind it, causing an intermittent connection that only shows up under vibration. Push on the lamp with the circuit live. If it flickers or cuts out, replace the mount and inspect the harness for chafe damage while the lamp is out.
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
Need the part, not just the reading?
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.