The 1960-66 Chevy C10 pickup came standard with a small rear window at the back of the cab. However, buyers who wanted improved visibility and a more "open" appearance could select a big window as an optional upgrade. For big-window trucks, the GM assembly line stamped a larger hole in the outside of the cab and welded on a matching interior window panel before installing weatherstrip and glass. Today, many C10 owners choose to upgrade their small window trucks with a big window conversion. Old Anvil Speed Shop recently published a video that shows each step of the process.
Old Anvil's Big Window Conversion Guide
Old Anvil Speed Shop, located in Orange, CA, converted a beautiful 1965 C10 from small window to big window configuration, and took the opportunity to film the process. The shop sourced many of the necessary parts from the Classic Industries GM Truck catalog.
The most important item for this conversion is the OER Authorized inner back window panel, which will be bonded and spot-welded onto the inner shell of the C10's cab. Classic Industries also offers the large back window glass and weatherstrip.
Speaking of weatherstrip, the first step of the process is to separate the inner weatherstrip from the cab with a small pick. Then the rear window glass can be carefully removed from the outside:
Once the glass is out, a few additional items need to be removed, such as the dome light and door weatherstrip.
A gauge cut to 3/8-inch and a Sharpie marker were used to mark the outside circumference of the area that will be cut to fit the big window glass.
The small rear window inner panel will need to be removed, so a sander was used to grind down all the spot welds. Care was taken to avoid grinding too deep and damaging the cab shell or the paint on its exterior.
A reciprocating saw was used to cut around the inner edges of the panel — one step closer to removal from the outer shell.
The weakened spot welds around the outer circumference were pried apart. This separated the panel and allowed the Old Anvil crew to remove it from the truck.
To remove the exterior portion of the cab, a Milwaukee Nibbler tool was used to cut off the majority of the sheetmetal. Then the edges were cleaned up and trimmed to the Sharpie line with a reciprocating saw.
The new OER Authorized inner back window panel was test fitted in the cab, ground down to bare metal along the edges, and prepped for spot welds. Panel bond adhesive was applied along the other edges.
With the inner window panel clamped into the cab and the adhesive drying, a welder was used to permanently tack the panel into place. Then it headed into the paint booth for a matching coat of blue and white paint.
Once the paint was dry, new weatherstrip was installed along the edge of the window opening.
Finally, the window was inserted and the conversion process was complete. The big window conversion for this C10 reduces blind spots and looks great, so it's a worthwhile upgrade for owners who are comfortable doing a little light metalwork.
Check out the full DIY conversion video from Old Anvil TV below:
Looking for Chevy C10 Parts?
Classic Industries offers thousands of parts for 1947-2008 Chevy and GMC trucks, ranging from small parts like weatherstrip and emblems to body panels and suspension kits. Click the button below to get a free full-color Chevy and GMC truck parts catalog:
