Here is how to replace the window lifting gas springs for a truck topper. If you have a truck topper, and it won’t stay open because the Hydraulic spring struts have gone bad, this video will show you how to put new hydraulic lift springs on your camper shell rear window. Installation is very easy. You just use a screwdriver to pop the old hydraulic strut springs off, and then pressure fit the new ones on. The only tricky part in replacing the hydraulic window lifting springs on a truck topper rear window door is buying the right size. you need to measure the distance between The middle of the balls that the hydraulic spring strut connects to. You need to do this when the truck topper rear window is open and when it is closed, and buy the right hydraulic truck window lift spring with the correct open and closed dimensions. You also need to buy a spring with the correct tension, measured in pounds. On my truck it works very well with two 30 pound springs. If it all possible, you’ll want to look for a label on your old springs, which will tell you the open and close distance, and the pounds of pressure it’s supplies. Watch this video, and it will be easy for you to replace the hydraulic lifter support springs on your truck topper.
Here's where to buy new hydraulic springs for your truck topper:
https://amzn.to/2WWYnr7