The best choice depends on the hinge style and part number used by your fiberglass tonneau cover. Of these options, the Dee Zee slide is specifically described for a Guardian tonneau cover, while the two 35440400 replacement sets are intended for compatible Trifecta and Extang tri-fold covers—not fiberglass covers generally. The gas struts and stainless butt hinges may suit some custom repairs, but check dimensions and mounting requirements before buying.
| Product | Best For | Key Check |
|---|---|---|
| Dee Zee DZ 9787 | Guardian cover slide replacement | Confirm cover model |
| Four-piece 35440400 kit | Compatible tri-fold center hinge repair | Match part number |
| Two-piece 35440400 set | Replacing one or two center pieces | Match part number |
| IAQWE gas struts | Adding lift support to a suitable lid | Check size and force |
| Adiyer butt hinges | Custom box or lid hinge work | Check mounting geometry |
Dee Zee DZ 9787 Tonneau Cover Hinge Slide
This slide is the most directly tonneau-specific option in the list. It is made from lightweight aluminum extrusions with a black powder-coated finish, and its stated purpose is to allow access to the rear of a truck bed with a Guardian tonneau cover.
Best for: Owners repairing or replacing the hinge slide on a compatible Guardian cover. It was selected because its listed use is specifically tied to a tonneau cover, rather than general furniture or lid hardware.
Check before buying: The provided details do not establish compatibility with fiberglass covers generally or with other cover brands. Confirm that your cover uses the DZ 9787 slide before ordering.
Four-Piece 35440400 Center Hinge Kit
This kit includes four replacement center hinges made from high-strength PETG. The listing identifies fit for reference part number 35440400 and describes compatibility with Extang Trifecta and eMAX models. It is intended to repair cracked, worn, or broken hinge sections and restore folding and locking function without replacing the whole cover.
Best for: Owners of a compatible tri-fold cover who need several center hinge pieces. The four-piece set may be a better fit than a smaller repair pack when multiple hinge areas need attention.
Check before buying: Do not assume the stated fit applies to every fiberglass tonneau cover. Confirm your original part number and cover model; the listing does not establish universal fiberglass compatibility.
Two-Piece 35440400 Hinge Center Set
This aftermarket set contains two black PETG hinge center pieces for select Trifecta and Extang tonneau covers that use reference number 35440400. The listed purpose is replacing a damaged, worn, cracked, or missing center section to help restore normal folding function.
Best for: Buyers who have verified the 35440400 reference number and need one or two replacement hinge centers. It offers a smaller repair set than the four-piece kit and includes a spare if only one area needs replacement.
Check before buying: Compatibility is described for select covers, not all brands or fiberglass lids. Verify the original part number and hinge shape before purchase.
IAQWE 20-Inch Gas Struts
This pair of lift supports is rated at 200 pounds or 889 newtons per strut, according to the product name. Listed dimensions are 20 inches extended and 12.13 inches compressed, with a 10 mm ball joint diameter. The manufacturer describes uses including truck tonneau covers, toolboxes, RV storage, and access hatches.
Best for: A buyer adding or replacing lift support on a lid where the strut length, pressure, and ball-joint connection match. The listing also provides guidance for choosing support based on lid size and opening angle.
Check before buying: These are gas struts, not hinge replacement pieces. Incorrect force or dimensions may not suit the lid, so measure the existing setup and use the product’s selection guidance.
Adiyer 4-Inch Stainless Butt Hinges
This two-piece set has 4-inch folding butt hinges made from 304 stainless steel, with a brushed finish and mounting screws included. The listing describes them for furniture doors, cases, lids, and wooden boxes, rather than identifying a specific truck-cover fit.
Best for: A custom repair where a conventional butt hinge is appropriate and the mounting surfaces and dimensions match. Stainless construction and included screws are useful details for buyers considering general-purpose hinge hardware.
Check before buying: No tonneau-cover or fiberglass-specific compatibility is stated. Avoid treating these as a direct replacement for a proprietary cover hinge without checking the mounting pattern and lid design.
Buying Guide: How to Choose a Fiberglass Tonneau Cover Hinge Kit
Does the replacement need to match a part number?
Start with the cover label, owner documentation, or the number on the existing hinge. The 35440400 sets are listed for select Trifecta and Extang covers, while the Dee Zee slide is described for Guardian covers. A shared purpose does not guarantee interchangeable dimensions or mounting points.
Is your cover hinged, folding, or lift-supported?
Identify the failed component before shopping. A center hinge joins sections of a folding cover; a slide can help a cover move for bed access; gas struts support an opening lid. A general butt hinge serves a different function and should not be substituted solely because it is labeled a hinge.
What should you measure?
- Record the existing part number, hinge shape, and mounting-hole pattern.
- For gas struts, compare extended and compressed lengths, joint size, and required force.
- Check how the replacement attaches to the cover and truck bed before removing hardware.
- Confirm the replacement is intended for your cover style and material.
Fiberglass-specific fit is not confirmed for most products in this selection. When the listing names a cover family or part number, treat that as a compatibility requirement, not a general recommendation for all fiberglass covers.
Frequently Asked Questions
Are these kits compatible with every fiberglass tonneau cover?
No. The listed products specify limited cover or part-number compatibility, or do not state fiberglass fit. Verify your cover model and hinge details.
Which option is a direct tonneau-cover part?
The Dee Zee DZ 9787 is identified as a tonneau cover hinge slide for a Guardian cover. The 35440400 sets are replacement center hinges for select Trifecta and Extang models.
Can gas struts replace a broken hinge?
No. Gas struts provide lift support; they do not replace the hinge mechanism. They may be relevant if the cover or lid requires support while open.
How do I choose between the two 35440400 sets?
Both are listed for compatible covers using reference number 35440400. Choose based on the number of center pieces needed: one set contains four pieces, and the other contains two.
Can I use stainless butt hinges on a fiberglass cover?
The product listing does not establish fiberglass-cover compatibility. Check the mounting method, dimensions, and cover construction before considering them for a custom repair.