The Liftmaster K74-39307-1, CONTROL BOX ONLY, PLASTIC, LA500UL is a LiftMaster replacement Plastic control box enclosure used to restore the correct mechanical or electrical housing, drive, or service assembly on the matching operator. This is the type of part that should be selected by the operator model number and the LiftMaster replacement parts diagram, not by appearance alone. Similar LiftMaster and Elite service parts can look close in photos while using different mounting points, wiring locations, sprocket sizes, switch layouts, or enclosure dimensions.
For a service technician or parts-counter check, the important question is whether the original operator calls for K74-39307-1 or one of the related numbers listed below. When the correct part is used, it helps protect the operator assembly, maintain proper chain or switch alignment, or restore the intended electrical function without forcing a substitute part into the system. If the original part is damaged from impact, corrosion, water intrusion, heat, worn bearings, chain misalignment, or electrical failure, inspect the surrounding parts before installing the replacement so the same failure does not repeat.
This part is commonly associated with the following LiftMaster applications when confirmed by model number, configuration, and the replacement parts diagram:
Do not use for LA400UL, LA412UL, older LA500 non-UL, LA500U plastic box, or LA500UL metal control box applications unless the parts diagram calls out K74-39307-1.
| Feature / Specification | Details |
|---|---|
| Manufacturer | LiftMaster |
| Product Type | Plastic control box enclosure |
| Part Number | K74-39307-1 |
| Application | LA500UL swing gate control box replacement |
| Compatible Operator Type | 24VDC linear actuator swing gate operator |
| Material / Finish | Plastic enclosure |
| Included Components | Control box enclosure only unless otherwise supplied by manufacturer |
| Notes | Match by LA500UL model and parts diagram before ordering. |
The following numbers and search variations may be associated with this item, but related numbers should not be treated as automatic replacements unless confirmed by the manufacturer parts diagram:
Before replacing this part, inspect the connected hardware, wiring, mounting points, chain path, limit system, enclosure seal, and operator structure as applicable. A failed service part is often the visible result of another issue such as gate drag, poor alignment, water entry, worn chain, loose hardware, or damaged wiring.
Gate operators are safety-related systems. Do not bypass monitored safety devices, limit systems, protective covers, or electrical protection to make a part fit. If the operator has unsafe movement, damaged wiring, failed safety devices, or high-voltage concerns, have the system inspected by a qualified gate technician.
K74-39307-1 is commonly listed for LiftMaster LA500UL swing gate operators. Match the operator model and replacement parts diagram because LA400UL, LA412UL, LA500U, and metal control box versions use different enclosure part numbers.
This item should be treated as the control box enclosure only. Logic boards, batteries, wiring harnesses, transformers, and accessory parts should be confirmed separately unless the seller or manufacturer package states otherwise.
No. The plastic and metal LA500UL control boxes are different service parts. Use the enclosure style shown on the original installation or the exact parts diagram for the operator.
Common reasons include cracked plastic, damaged hinges or latch areas, weather exposure, impact damage, or an enclosure that no longer protects the board, transformer, wiring, and batteries correctly.
Check the operator model tag, existing box style, hinge and mounting layout, battery space, and the LiftMaster parts diagram for K74-39307-1.