2019-2021 GMC Sierra Fenders

Our aftermarket GMC fenders for 2019-2021 GMC Sierras are handcrafted right here in America to ensure the kind of quality, durability, and craftsmanship you’ve come to expect from Advanced Fiberglass Concepts. Each Sierra fiberglass fender is made specifically for your model and year and designed for a seamless transition between the factory panels and our aftermarket body panels. These Sierra prerunner fenders are a perfect match with our 2019-2021 Sierra bedsides to create a build that is ready for any terrain.

• Allows for larger tires without rubbing issues
• Fiberglass fender is hand-laid in America to ensure quality
• Molded specifically to replace Sierra fenders
• Designed to be long-lasting even during the toughest rides and climates
• Made in the USA
• Comes standard in semi-gloss white
• Part Number: AFC 172 (4” Flare 2” Rise), AFC 172-BC (AT4/Denali Bumper Caps), + AFC 172-L (Fender Liners) 

GMC Sierra
2019 – 2020 – 2021

INSTALLATION INSTRUCTIONS: FENDERS

All of our products are fairly easy to install. You will need a few hand tools and a few hours of time, depending on the products you have purchased. Also, you will reuse most of your stock hardware during this installation—it is typical to have a few screws and bolts left over, however. Advanced Fiberglass Concepts LLC does recommend that a professional install for a seamless fit install these products.

Tools required for most install:

• Socket set
• Drill and drill bits
• Screw drivers (Flat head and Phillips);
• 120 grit sand paper (optional)
• Metal Shears or Sawzall or Plasma Cutter

Step 1: Open hood and remove bolts holding the fender down under the hood, behind the doors, under the door areas, and behind the bumper.

(Note: not all trucks have bolts located in all the areas mentioned above)

Step 2: Remove plastic liner from fender, marker lights, and headlights.

Step 3: Remove steel fender by skinning the exterior fender from the inner shell from truck once all the bolts have been removed.

Step 4: Set fiberglass fender in its place and mark the holes that need to be drilled. (Note: Most fenders have markings where to drill, but some do not)

Step 5: Drill holes out with a 3/8 drill bit—the reason for this is so you can move the fender back and forth to align the gap in the hood and door area. To get a consistent hood and door gap, use a mixing stick between door and fender.

Step 6: Reinstall fiberglass fender and begin to bolt it down-- but do not tighten all the bolts until you have the right gap. We recommend using a mixing stick to get the same gap at the door and hood area. Once you have the gaps spaced, tighten down the bolts. Do not over tighten! The fiberglass fender will make sounds like it is cracking—this is common as it is fiberglass, so do not worry.

You will need to be patient to get a good fit. You may need to sand some of the fender down so it does not stick out too far from the rest of the body. This is because fiberglass fenders are thicker than steel. If the hood sits too low or too high, you can adjust it by turning up or down the rubber height adjuster at the front of the hood located in the core support, or hood.

Please keep in mind, although all of our products are made from factory steel fenders, hoods, and bedsides, there is a difference in fit because of the thickness of the fiberglass compared to steel. Therefore, please be patient when you start this job.

Not all trucks are the same so you may need to remove the grill and lights on some models. If you need further assistance with this installation, feel free to call us—one of our techs will be more than happy to help you.

These instructions are useful for all fenders sold by Advanced Fiberglass Concepts.—therefore some of the steps may not be needed or should be slightly altered to suit your particular vehicle and product needs.

We do our best to have as much inventory as possible. However, if they are not in stock, then our lead-times are normally 2-4 weeks from order date. Please contact us through live-chat, email, or phone to check inventory and current lead-times.

All our products are shipped through LTL Freight carriers. Shipping prices are calculated in the checkout area. Our products can get expensive to ship because we ship all our products with premium LTL Freight carriers to ensure they are not damaged (All orders are insured in case of potential shipping damages). Other factors that control the shipping cost are the size of the package, weight, overall destination, and nature of the product (Fiberglass), which all play a large role in shipping costs. To help cut down the shipping cost, ship to a commercial address.

The panels are made from fiberglass (or carbon fiber if requested at an additional cost). We use a proprietary blend of polyester resin which is paired with our fiberglass mat and cloth. This combination of resin and fabric provides the strength and flexibility to make our body panels a superior product.

Products come semi-gloss white unless requested in a specific gelcoat color. We do not offer color matching services. All gelcoat colors are generic colors and will not be an exact color match. Any body shop in your local area can color match our products. All products require prep work for paint.

All products require professional installation. Minor adjustments may be necessary. These are normal bodywork prep and installation steps and therefore NOT considered to be defective. Defective products must be brought to the attention of ADV Fiberglass within 20 business days of receiving the parts. Pictures are required to display true defects on the products prior to return. Any defects found beyond 30 days of receipt are no longer eligible for exchange or return. Issues found that are not directly caused by a manufacturing defect are not covered under any warranty offered by ADV Fiberglass (examples: acts of nature, neglect, misuse, imperfect weave, third-party mechanical, heat or any other damage inflicted by improper use of the products). This includes, but is not limited to, improper handling, improper installation by unauthorized dealerships or mechanic shops, damage inflicted by improper shipping, storage, or use of said parts. The warranty also does not cover any damage resulting from usage in unsafe environments, eg. Off-roading. To qualify for warranty coverage, all items must be inspected prior to accepting delivery. Any damage found during delivery inspection must be reported to the carrier before accepting delivery. If damages are reported after delivery, no warranty or coverage will be offered. ADV Fiberglass is not liable for any damages or injury as a result of the use of its products. Rest assured, we are known to provide the strongest and best fitting parts in the industry.

Advanced Fiberglass Concepts customer guarantee is that you can return your item within 30 days (20 business days) of receipt as long as it is returned in the original packaging and you pay for all shipping charges; original shipping fees are non-refundable. Products are non-refundable if mounted or altered in any way. Extra fees may be incurred for proper fitment and finish. Refunds will not be issued due to minor fitment or finish issues. All refunds are processed in 30 days (20 business days) after the order is returned. All orders have a 35% restocking/cancellation fee. All order(s) will be issued a restocking fee if the product(s) have begun production. No refunds, returns, or exchanges on wire transfers, rush orders, sale pricing, deposits, custom orders; carbon fiber, colored gel coat, and more. For all installs, we are not responsible for damages/malfunctions on aftermarket parts (Such as headlights, bumpers, and much more).