In the list of typical spots for rust to rear its ugly head on vintage cars, there are a couple areas that strike terror in the hearts of body guys. Both of them are results of leaky gaskets around the front or rear windshields. Up front, it's the cowl vent and A-pillar; in the rear, it's the trunk filler panel area.

We say terror because windshield areas are notoriously difficult areas to patch correctly due to complex shapes, inaccessibility, and often the lack of availability for good patch panels. A lot of the cars lingering in vintage salvage yards will have the same issues, so running across good used parts can be a challenge.

After our '67 Mercury Cougar—known around here as Max Effort—returned from mediablasting at Pacific Coast Powder Coating, our biggest surprise was that the bottom corners of the rear windshield had basically disintegrated. This is actually a super common issue on Cougars, especially those that were equipped with vinyl tops. We thought we had dodged the bullet since Max's top had been removed many years ago and the rust seemed small, but once again we learned that there is always more rust than meets the eye.

That's why we were revved up to hear about West Coast Classic Cougars' new replacement trunk filler panel for '67-68 Cougars. Though Cougars share nearly 100 percent of their chassis and suspension architecture with Mustangs, there really is nothing body wise that crosses over. That's really unfortunate since they seem to be predisposed to the same rust areas, but whereas Mustangs have a multitude of quality patch and replacement panels available on the market, Cougars have almost none. And good luck trying to find a used panel that's rust free.

After thanking the hot rodding gods for serendipitous timing, we sent one right over to Wes Adkins of Wild Wes Paintworks in Dover, Ohio, to mend Max. It's still a somewhat intimidating repair since most people haven't attempted it, but Adkins took the time to break down the steps and show exactly how it can be performed by anyone with a welder. We may be working on a Cougar here, but the steps will cross over to any vintage car unfortunate enough to need the patch.

Here's what was hiding under what at first appeared to only be a nickel-sized rust bubble. The curvature of the lip makes this a really difficult patch panel to make by hand, so a stamped piece is definitely worth the purchase just for the time and effort it saves.

The trunk filler panel is actually the top of a structural element to the rear of the body, so before cutting can begin Wes Adkins braced the under-structure that will not be removed with two 3/8-inch steel rods tacked into place.

Dozens of spot welds hold the panel in place, all of which must be ground down to separate the top and bottom panels. This is by far the most time-consuming part of the swap.

We want to leave the trunk water channel intact, but on the outer edge where the filler panel meets the quarter-panel, the spot welds aren't accessible. Here Adkins uses a cutoff wheel to cut the top panel away. Typically this area will have body sealer that will need to be removed first, but mediablasting removed Max's.