30 Again, a block of wood can be very handy when persuading sheetmetal to line up. The bottom of our quarter skin needed some help fitting our door alignment. Once fitted, the skin is tacked to the doorjamb to prevent movement. | 
31 The quarter extension is trial-fitted to the car, and the quarter skin is adjusted for a nice, flush fit. | 
32 Once the quarter skin is sitting where it needs to be, the MIG welder is called in, and the end of the skin is attached to the taillight panel. |
33 The top of the quarter skin is now ready to be welded to the original sheetmetal. The skin is butt-welded to the car like a floorpan. Using a reciprocating saw, the old quarter and new skin are cut together. Every few inches, the cutting is suspended and a tack weld is made. | 
34 Once the top of the quarter has been cut and tack-welded, the remaining old metal that was cut away is removed from the trunk area where it fell. | 
35 All that's left to do is close up the gap between each tack weld. The quarter skin is welded in small sections, using a wet towel to prevent the heat from warping the new skin. |
36 The completed weld is invisible to the casual observer looking into the trunk, but it can be felt. Of course, some grinding and a generous layer of primer and paint could conceal it. | 
37 Like all welds, the completed weld on the top of the quarter skin requires grinding. Care needs to be taken to ensure that the original contour of the top of the quarter is maintained. Welding the skin on in this fashion minimizes plastic filler usage and puts the filler in a narrow line along the top of the fender versus across the side of the skin in a typical "flange" repair. | 
38 Note the nice-looking door-to-quarter gap and the ground weld. A small amount of body filler and some primer and the quarter looks original. Tune in for our final metal repair stories on our '66 hardtop project, including taillight panel and cowl patches in the coming months. Then it will be time to break out the paintbrushes! |
Decisions, Decisions, Decisions...
When deciding upon the type of quarter-panel you need or would like to use for your Mustang's sheetmetal repairs, you must take into account several things. First and, to some, foremost is price. The quarter skin can be purchased for around $59-$69, whereas the full quarter is in the pricier neighborhood of around $150-$200. This means you could purchase two skins for less than the cost of just one full quarter. But sometimes a full quarter is needed. If the rearmost part of the quarter (where the quarter extension bolts to) is damaged and beyond basic body repairs, the only way to obtain this section is via a full quarter-panel, thus a quarter skin would be useless to you. In this sidebar, we have a few more photographs detailing the pros and cons of your choices. Take a look at these photos, then your Mustang, then your checkbook, and then order the appropriate parts.
As we state in the sidebar text, if this rearmost section of the quarter-panel is damaged, then a full quarter will be required to replace this section (unless you find a good used section to add to your skin). | 
If you install a skin and retain the original trunk lip, you can save your original sheetmetal date code stamp (arrow). A skin used on the driver side will also retain the wiring harness retaining tabs (though these can be transferred to the new quarter). | 
Whether you use a skin or a full quarter for your repairs, ensure a consistent door gap before and after the repair by either repairing or replacing your door hinges. New check springs and bin/bushing kits are available, as well as original and reproduction hinges. |
If you have major rust around the trunk lip area, the best way to repair the area is to install a full quarter with the lip included. Again, inspect your Mustang and see what type of metal repair is needed before making a decision. | 
The installation of a full quarter will require lead work. Some shops perform a continuous weld bead, then fill the area in with body filler. But lead is the correct way to install it. Make sure your shop has someone who has lead-working skills before you have them install a full quarter-panel. | 
When you make your decision as to which type of quarter-panel repair you wish to make, remember to insist on butt welding and not overlap welding. The quarter-panels are an integral part of the unibody and therefore necessitate strong welds with the use of a MIG welder. |