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I removed my slider and noticed that there was a plastic piece inserted into the metal frame on the top to compensate for the curvature of the window top. Is that normal for these aftermarket windows?
I removed my slider and noticed that there was a plastic piece inserted into the metal frame on the top to compensate for the curvature of the window top. Is that normal for these aftermarket windows?
Well, well. Finally someone who has come across this strange anomaly that I thought was unique to me. I bought a slider off of Ebay (first mistake) that was advertised as an OEM dentside window. It looked clean, but had this gray piece on the top that I just figured was part of the window due to my inexperience with these trucks at the time. When I received it I saw that it was a rough cut piece of plastic that sat in the channel and was easily removable. Thinking it was odd but still hoping the glass would work I brought it to the installer who promptly informed me that it was the wrong glass and what I had there with the plastic piece was something that folks would do to jimmy-rig a slider from another truck into a dentside. It would technically work but inevitably leak. I’m still trying to figure out what this glass fits so I can sell it to a good home. I think it might be off a bumpside or a Dodge.
Plastic piece was on top like yours. Flat top does not fit a dent. When I finally decided to cease the search for overpriced OEM sliders and went with an aftermarket one the part I received was curved on top and fit perfectly.
Last edited by Viper Pilot; Jan 25, 2026 at 01:29 PM.
My '77 has one since new, I never seen anything but the aluminum frame up top that has the lip that sets in the rubber channel. Way it's made, it sets the face maybe half inch out forms a channel for water to run off the sides.
No pics
Last edited by tbear853; Jan 25, 2026 at 02:24 PM.
What ViperPilot said about it inevitably leaking made me take a long look at it in the garage. I wanted to see why it would leak. After looking over I determined that b/c the rubber seal will on top ride on the plastic insert instead of the metal channel, the water will/could seep between the two and work its way who knows where. By following the rust trail around my rear window and along the floor below the window, I know exactly where the water will go. I guess my construction experience made me think of installing flashing, like roofing flashing, over the joint between channel and plastic.
I will trace the aluminum flashing (very thin) to the plastic insert and silicone it in place. So the rubber seal will be riding on the flashing instead of the plastic. Water would have no chance of getting in the channel. That should seal it up, right? Am I willing to take the chance? Huh. I don't know. Don't even know if it would work. I think a new aftermarket one costs about $500. Well, my possible solution is something to think about.
You can see the plastic insert sloping upward. The beginning of the plastic insert in the channel.
It sounds, reads ..... like it's an aftermarket slider intended to fit a broader range of years and the piece is an adapter to fill the channel in the cab that arches. Later trucks used thinner glass than a '73-'79 I think and if the slider was intended for them, the sliders lip might be too thin for a leak proof seal in a wider channel. Mines has had the rear seal replaced, but the rubber seal we used was for a '73-'79. I think the opening size is same up into the '90s.
The above shows two strips, but they are the channels inside the frame.
The frame on my '77 is a good deal thicker front to rear than the rubber, it has overhang outside the rubber. My truck is covered ice over snow and it's 10 degrees, but maybe this shows it?
Last edited by tbear853; Jan 27, 2026 at 12:28 AM.
That DK replacement window looks just like the one I purchased from JCWhitney way back in 1997 for my '77 F350 Crew.
It has the black anodized frame with the smoked glass.
I didn't have internet in 1997, _ _ _ so, I ordeed the Slider assembly from the JCWhitney catalogue. It fit perfect.
Two years later some idiot want thru the neighborhood and shot out windows, _ _ mine included.
The person shot thru the rear passenger door glass which also took out the rear slider glass.
I promptly ordered another replacement Rear Slider Window Assembly from JCWhitney, and voila, it fit perfect.
A good glass shop would know where to source another Slider Assembly if they are still available.
I used yellow contractor's string to Rope the Glass and Rubber seal in place with the wife holding the assembly from outside.
I was inside the cab pulling on the string, and it shoe-horned-in very nice for a non-glass guy.
JCWhitney today I believe is Carparts.com.
And, not so sure they still offer a replacement rear slider window assembly.
Thanks for all the info, guys. When the time comes I will lay it out on the bench with the rubber seal, and look it over and decide how to proceed.
I did go out and measure the rear window opening. In the center of the window opening it is 1/2" taller than on either end.
I removed my slider and noticed that there was a plastic piece inserted into the metal frame on the top to compensate for the curvature of the window top. Is that normal for these aftermarket windows?
I don't know how I did it, but I just realized that I misread your initial question. My apologies.
Reply ..... YES, Would have to be so that the left and right side rigid glass panes could slide apart to open. Mine is as Ford sold it (except it is currently sealed shut ... but it can be reverted to operational easy enough if desired) and it has the plastic like insert in the frame.
Some how, I got the impression that your frame for the glass was straight, but there was a plastic piece above it that adapted straight window frame to curved top of opening in cab back. Like I say, I can't explain my misreading. I see now, I guess I was right then above in post 7
Last edited by tbear853; Jan 27, 2026 at 12:24 AM.
Some how, I got the impression that your frame for the glass was straight, but there was a plastic piece above it that adapted straight window frame to curved top of opening in cab back. Like I say, I can't explain my misreading.
Yeah, that was my understanding of the post as well and the situation I found myself in. After the OP posted pictures I think his issue is a little bit different. This is a picture of the crap I paid $350 for from the Ebay ad. You can see the plastic piece at the top that disguised it as a dentside window.
Last edited by Viper Pilot; Jan 26, 2026 at 11:51 AM.
Yeah, that was my understanding of the post as well and the situation I found myself in. After the OP posted pictures I think his issue is a little bit different. This is a picture of the crap I paid $350 for from the Ebay ad. You can see the plastic piece at the top that disguised it as a dentside window.
Viper pilot: That is exactly what I have. The frame is straight top and bottom, but a piece of plastic or plexiglass has been inserted into the track on top to compensate for the curved window top of the cab window.
Viper pilot: That is exactly what I have. The frame is straight top and bottom, but a piece of plastic or plexiglass has been inserted into the track on top to compensate for the curved window top of the cab window.
OK, now we're back on the same page. The pictures you initially posted had me turned around a little bit.
So yeah, we're in the same boat. That plastic piece is clearly something that people put in there to try and make a window that isn't intended for the dentsides "fit". Personally, I wouldn't trust what you have and would try to find the correct part. However, if it wasn't leaking too terribly you might be able to get away with running it again. .
Last edited by Viper Pilot; Jan 27, 2026 at 08:39 AM.
The plastic insert is finely cut. That makes me wonder if it was installed at the aftermarket factory. But where it comes from is not important.
What is important is than the rubber seal, for about a foot, rides on that plastic, not on the metal ridge or lip that it is sealed to around the perimeter of the window. That would indicate to me that that is where the window mechanism is leaking. Where the seal crosses from metal flange to plastic is the weak point. When it comes time to install or refurbish, I will take a long hard look at the entire slider window assembly. Thanks one and all. If I don't feel confident that I can make it seal against the rain, then I'll get a new one.
I don't know how I did it, but I just realized that I misread your initial question. 
My apologies. 
I see now, I guess I was right then above in post 7
