When it comes to customizing classic trucks, one of the tasks at hand is cleaning up the stock body lines while gaining functionality in the process. For '73-87 Chevrolet and GMC truck owners, the problem just got a lot easier thanks to One-Piece Products of Whittier, California, and the introduction of their one-piece window kits. Installing a one-piece window kit on a truck is one of those rare projects that seems like it would be a lot of work because of the dramatic changes it produces, but in reality, it's quite simple.
We thought a good way to really put the one-piece window kit to the test would be to buy a beat-up old door from the junkyard and see if there were any problems. Typically, most C-10s seem to end up with a pair of those big, ugly West Coast mirrors strapped to the door, ultimately ending up with torn-out bolt holes and warped to boot. Our door was no exception. We didn't worry about the holes, but we did address the area below the window scrapers, which needs to be straight. The best way to check it is to look at it as if you were trying to find a good two-by-four. The bodyline must run parallel with the window glass. The next step is to make sure the area isn't flimsy. One-Piece Products includes a steel reinforcement bar to stiffen the area where the vent window track/brace is removed. With the vent window assembly removed, there are three screw holes that need to be filled. You can use the three plugs included in the kit, or, as we are doing with our '75 C-10 SS496 project, weld the holes up.
From here, our next step was to remove the front and rear window tracks, then make the necessary modifications explained in the directions. For the rear window channel guide, the kit includes a bracket with a built-in 4-inch extension that moves the channel closer to the door latch. In front, because the vent window assembly has been eliminated, the kit includes a new window channel to accommodate the new, longer, tempered one-piece door glass. Also included is a template indicating where the new holes need to be drilled, with the largest being 1 1/4-inch. Before we could permanently install the one-piece window, we went through a series of minor steps illustrated here with photos and captions. All in all, the installation went pretty smoothly, and when we tackled the other door, thanks to familiarity, it only took us about half as long to complete.

Here's the stock C-10 door...

Here's the stock C-10 door with its world-famous whistling vent window. In addition to a custom appearance, converting to one-piece windows eliminates irritating vent window (wind wing) noise.

The one-piece window kit comes...

The one-piece window kit comes packaged complete with everything needed to handle the conversion. It's available through Brothers and One-Piece Products.

Step one was to remove the...

Step one was to remove the door panel by removing all the visible screws, including the window's regulator handle, and then lift it straight up and off.

Next to go was the vent window...

Next to go was the vent window assembly. We removed three Phillips screws from the door's window frame and then moved lower.

The kit includes three plastic...

The kit includes three plastic plugs to fill the vent window mounting holes. For a truck that's going to be painted afterward, it would look cleaner if these holes were welded up.

The last bolt to be removed...

The last bolt to be removed to extract the vent window assembly was at the door's front lower portion.

In preparation for removing...

In preparation for removing the door window glass, One-Piece Products' Benjamin Tapia removed the stock window scrapers from the door. The kit includes new scrapers custom-made to fit the one-piece windows.

To pull the vent window assembly...

To pull the vent window assembly out of the door, Ben cranked the window all the way down and then withdrew it.

To remove the door glass,...

To remove the door glass, Ben cranked the window all the way up to line the rollers up with the notches on the stock window glass.

With the rollers detached...

With the rollers detached from the stock window glass, Ben removed it from the door.

Ben used the template supplied...

Ben used the template supplied in the kit to mark where new holes for the one-piece window conversion had to be drilled into the door.

To gain access to the new...

To gain access to the new one-piece window glass, he bored a 1 1/4-inch hole into the door, using the template for a guide. He flipped the template to do the other door.

After drilling the points...

After drilling the points indicated on the template, Ben elongated the two holes with a Uni-Bit to provide for window adjustment.

To size the door frame so...

To size the door frame so the new window channel material would fit correctly, Ben twisted a ball-peen hammer handle in the channel to open it up.

The rear stock window channel...

The rear stock window channel was removed from the door...

...then a 4-inch extension...

...then a 4-inch extension bracket included in the kit was bolted on with special hardware also included in the kit.

To clear the one-piece window...

To clear the one-piece window glass, Ben cut the arm extending on the door lock cylinder in half, then...

...bent the lever on the door...

...bent the lever on the door lock linkage inward. Ben suggested the window should be raised and lowered afterward to ensure it doesn't hit.

Ben positioned the one-piece...

Ben positioned the one-piece window at a 45-degree angle to install it into the door. As he lowered the glass into place, he twisted it horizontally, then connected the front and rear rollers, leaving the mounting hardware loose.

To handle the final adjustments,...

To handle the final adjustments, Ben rolled the window up and down, checking for alignment as he tightened the bolts down completely.

With the one-piece window...

With the one-piece window installed, the last step was to smooth out a bump that's on all C-10 door panels so the new One-Piece Products window scrapers will lay flat.

All that was left was to rivet...

All that was left was to rivet the window scraper in four places onto the door panel, then reattach the door panel to the door.