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’77 C10 | Installing Mar-K’s Body-Side Molding

Installing Mar-K’s Body-Side Molding on a ’77 C10!

Nothing sets off an early squarebody more than a complete set of body-side moldings. A few different manufacturers make this molding, and we have used them all. However, we have found that the molding made by Mar-K is of the best quality, resulting in the best overall fit and finish. Although offered in individual pieces, we opted to get the complete upper and lower sets with clips. Mar-K moldings are made from thicker-gauge US aluminum. Finished off with black or 1977 only gold accent stripes and are then bright anodized for protection and a shiny finish. 

We are building a ’77 C10, but we decided on the black accents as it fits with the build a little better. If your truck had this molding from the factory, the installation is relatively straightforward, but the install process can be a bit daunting if it did not.

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Our truck was an original Silverado with factory trim; however, we replaced several panels, and the only place the original holes remained were the cab corners. Mar-K offers a couple of options for attaching the moldings. One option is to use clips with an adhesive backing. Another option is to use a combination of clips that consist of metal clips with studs and nuts and the aforementioned adhesive clips. Both include screws that are used for attachment. We used the combo kit as we felt it would provide a more robust installation.

With our truck, we were in the final mockup stages before paint. This is a perfect time to do the installation and drill all the necessary holes.

This can also be done on a painted truck, but you must use extra caution and use lots of masking tape. Make sure to measure twice and drill once. Also, it is crucial to make sure all of the bodylines are aligned correctly. If not, it may be time to replace the cab bushings. It is best to have a friend to assist in the installation process. We asked our dad to help; there is nothing better than a shop project where you can spend quality time with your dad!

Mar-K’s Body-Side Molding
Packaged in heavy cardboard and Styrofoam ensures the kit arrives damage free.
We laid all of the molding out as it would go on the truck. Ensure each piece was accounted for and not damaged.
Mar-K’s Body-Side Molding Kit
The quality of the parts is evident in the horseshoe fender molding as the bends are nice and clean with no rippling. The nuts used on the metal clips with studs have a rubber seal to prevent water leaks into areas such as the cab corners. We laid out all of the attachment hardware and sorted to make it easier to access each piece when needed.
Before installing the new Mar-K moldings, we need to install the wheel opening molding so we can ensure we are placing the body-side moldings in the correct location.
Installing the clips onto the molding is as simple as sliding into the channel through the opening in the back of the molding.
Although our truck has holes in the cab corners, we chose to start at the front horseshoe and work our way to the rear. The front fender molding is the hardest to install as it takes the most studs and has the most holes to drill. Slide the connector into the horseshoe molding to ease installing the upper fender molding.
We have seen the molding all over the place, but we believe it looks best when the top lines up with the bodyline. Hold the front horseshoe molding to the fender and line up the molding’s outside edge with the fender’s bodyline. Also, ensure it fits snugly to the wheel opening molding. Once positioned where you want it, hold it in place with several pieces of masking tape.
Mar-K’s Body-Side Molding installation
Slide the upper fender molding into the connector, line up with the bodyline and tape into place. Minor adjustments may be needed with the horseshoe to ensure everything lines up correctly with the bodyline.
Taping Mar-K’s Body-Side Molding on a 1977 C10
Next, tape the upper door molding in place while ensuring it lines up with the bodyline and the fender molding.
Taping Mar-K’s Body-Side Molding on a 1977 C10
As you can see here, the holes in this cab corner were low. We had to elongate the holes to get the trim in the proper position. Luckily, the holes on the driver’s side were perfect.
Align the upper bedside molding with the bodyline and tape in place. Ensure it is flush with the front edge of the bed and the rear edge by the tailgate. We used a short piece of a paint stir stick to bridge the gap between the cab and bed so we could ensure perfect alignment
Installing Mar-K’s Body-Side Molding on a 1977 C10
Now that we have all of the upper molding in place, we can place the lower moldings. We started at the rear and worked our way forward for the lower moldings. Beginning with the lower rear bed molding, align it with the back edge of the bedside by the tailgate and then with the wheel opening molding on the front. Make sure the outer edge aligns with the bodyline below the taillight. The molding will have a slight drop toward the front and will be roughly 10.5 inches from the top molding at the wheel well.
Attach the lower front bed molding using masking tape as was done for the top molding. There should be 13 5/8 inches between the top and bottom moldings. To ensure the proper distance, we took two paint sticks and taped them together at the appropriate length to create a measuring stick or what we call a story stick. It makes quick work of keeping the spacing consistent.
Follow the same steps using the story stick to place the remainder of the lower moldings in place.
Installing Mar-K’s Body-Side Molding on a 1977 C10
Follow the same steps using the story stick to place the remainder of the lower moldings in place.
Now that everything is taped in its proper place, we can begin measuring where we need to drill holes. For the front fender, several holes need drilling. Placement for these holes is defined by the circled access holes inside the fender.
Place a straight tape line on each side of the molding to identify the edge of the molding once it is removed.
Place a small piece of tape behind where each screw hole needs to be drilled. Using a pen or pencil, mark the hole placement on the tape through the molding. There are six screw locations on each side, the rear of upper and lower fender, front of upper and lower door, and rear of upper and lower bed moldings.
measuring Mar-K’s Body-Side Molding on a 1977 C10
To find where the holes should be drilled on the front fender, we used a level to mark the edge of the access hole with a piece of tape on the fender’s top.
measuring Mar-K’s Body-Side Molding on a 1977 C10
We then used that same piece of tape at the top of the fender to align the level and find the hole location on the outside of the fender. Once the level is level, place another piece of tape by the molding. Follow this same process for the other holes to be drilled in the fenders.
Body-Side Molding on a 1977 C10
You will also need to place tape to mark hole locations for the upper and lower door trim. Also lower front fender trim and lower bedside trim. Although not marked in the photo, you will need to drill three additional holes for the cab corner trim—two for each upper and one towards the front of the cab for the lower. Once marked, you can remove the molding. Your truck should look something like this. Stud locations are circled in the photo.
Taping off where to drill for Mar-K’s Body-Side Molding on a 1977 C10
Once the moldings are removed, you can mark the proper location of the holes to drill. We know from previous steps where the approximate location should be; now, we need to determine the exact placement. Find the center of the molding by measuring between your two tape lines and dividing it in half. Now mark the drill center based on this measurement and the tape locations added in earlier steps.
Drilling holes for a Mar-K’s Body-Side Molding kit on a 1977 C10
Using a 1/8-inch drill bit, drill each hole. Use caution and go slow, especially if you are working on a painted surface. Now is also the time to drill the screw holes with the appropriate drill bit.
Final install of Mar-K’s Body-Side Molding on a 1977 C10
Now you can install the clips and permanently attach the molding. Be sure to properly clean the surface where adhesive clips will be for proper adhesion. Use a wax and grease remover or rubbing alcohol to prep the surface. In our case, we attached it with the studs. Not using the adhesive-backed clips as we are going to be removing for final bodywork.  We are delighted with the final product and cannot wait to see it all together and with paint.

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