While these sheetmetal repairs are usually fairly simple to tackle, a truck with a large amount of repairs can prove to be daunting, oftentimes causing one to lose motivation, effectively stalling the project. But if we concentrate on each repair individually, dividing them up into bite-sized, daylong tasks, those duties can be tactfully tackled.

The fact that nearly every panel for most makes and models is available in the aftermarket makes for repairing these old trucks even easier. A quick peruse through websites like LMC Truck’s showcases said availability. So, it should come as no surprise that when it came time to start repairing the sheetmetal on our 1964 C10 project we picked up LMC Truck’s catalog and started a wish list of parts and panels. We started at the worst points, which are typically the lower sections of the cab where 70-plus years of crud tends to gather, creating a petri dish of moisture that ends up attacking the iron in the sheetmetal, resulting in rust, which ends up eating away the tin in the form of cancer. This is typically visible on the surface by small bubbles in paint, surface rust, or full-on sections of missing metal. Whatever the method of revelation, Confucius says, “It’s gonna be worse underneath!”

And that’s exactly what we discovered when we began peeling back the layers on our C10 cab. We could tell that the section at the bottom of the A-pillar was pretty bad, but only after removing the outer rocker panel and the lower A-pillar did we realize the amount of damage we were up against. No fear, however, as we had a great source in LMC Truck to help us repair our cab and get our project pushed along further down the road toward completion.

This month, we’re going to start by repairing the A-pillar section and the outer rockers. We’ll follow up in the coming months as we continue the repairs necessary on the C10.

2. … but some damage, like this area that had been previously repaired, wasn’t so obvious. The lower rear cab corner had also received its fair share of cancer rot and damage that will need to be repaired.

4. Spot welds tend to reveal themselves as small craters in the sheetmetal, but sometimes they can be difficult to find. One small spot weld can seemingly hold an entire panel in place. A couple passes with a sheet of sandpaper can help reveal the low spots, just like when doing bodywork.

6. When all the spot welds have been removed, the entire rocker panel is ready for removal.

9. We’re going to use four repair panels from LMC Truck to repair the lower section of our cab this month. First, we’re going to repair and replace the inner section of the lower A-pillar of each side of our cab with a new repair section (PNs 38-9200 and 39-9201). Next, we’ll tackle the outer rocker panels (PNs 38-9048 and 38-9049). We’re going to hold off on the cab corners (PNs 38-9050 and 38-9051) for a future story.

10-11. The lower A-pillar is going to receive our attention first as this section needs to be intact before the outer rocker panel can be installed. As is typical with any rust damage, it’s much worse on the inside than the outside. This is because this type of damage starts with trapped dirt, debris, and moisture inside the panel, rotting its way out. By the time it becomes noticeable on the outside, it’s ran rampant internally (as you can see here).

12-13. There are four fasteners that attached the lower A-pillar to the cab assembly. We’ll use these same holes to help align the new repair panel, but first the old, rusty fasteners need to be removed, the threaded captured nuts chased, and any offending sheetmetal trimmed away.

16. After trimming away the rotten A-pillar, the new panel is checked for fit.

17-18. We don’t need to replace every rusty section of sheetmetal on our cab as that might be a life’s worth of work. Instead, we’ll repair the worst and tackle the rest by blasting it away and treating it to prevent further spread. Here, the section of cab that will be covered by the new A-pillar repair panel is being blasted down to clean steel.

20. But first, we’re going to treat the inner structure with a couple coats of Self-Etching Weld-Thru Primer to help mitigate any further rust.

22. The inner structure of the cab’s rockers were just as rusty as that inner section of the A-pillar, and, like the A-pillars, the rockers received the same treatment from the blasting gun. Some further wire wheeling and sanding and they’re looking pretty good.

23-24. Since this inner section of the rocker won’t be receiving any welding, we can use something slightly more effective to thwart further rust damage. We found this Rust Destroyer at our local hardware store and used it to neutralize the existing rust and minimize any further damage.

25-26. After a bit of trimming and initial fit, the new outer rocker panel is temporarily held in place by a couple sheetmetal screws.

28. … while the gap along the bottom of the door is consistent.

31. Here, two panels have been clamped together and joined via plug welding.

32-33. The outer rocker panel has been welded to the cab assembly along both ends and along the top, and the plug welds sanded smooth.