This thread is very interesting and really highlights a major design flaw in the open top spacers. After seeing this I did some research into the oem strut design. The strut mount top is stationary and does not slid up and down in stock form. But, the strut mount is not designed to take the full load of the strut. The top of the strut is held in place in the mount by a thin collar, and then the top of the strut rests against the underside of the strut top bucket on the frame. This lets the force of the strut compression transfer to the frame. But, with an open top spacer, all of the force is placed on the strut top mount which wasn’t designed for it. When first installed everything likely seems fine, but with time the strut top fails, at which point there is no longer anything keeping it from sliding up and down within the open top spacer. The rate of failure obviously varies depending on how the truck is driven so it may take years for this to happen. But, I think it can only be a matter of time before all open top spacers will suffer the same strut failure, regardless of the brand name since they’re all basically the same design. The steel spacers like rough country shouldn’t ever have this issue since they are a closed top design and hold the strut top in place so the force of the strut is taken up by the metal spacer instead of being concentrated in the strut mount.