Got the wrong struts?

[olyelr]

IMO, you cannot really 'upgrade' from the GM suspension, as it is very well designed. If your rig is predominantly for serious off-road uses, then aftermarket suspensions may provide better results.

No strut lasts forever, as it is a wear item. In general, GM suspension last for up to 100,000 miles, but of course there are exceptions. The active GM suspension shocks/struts, like the ones that you have on your rig, are warranted for life, so if they have failed go get your replacements.

Warrantied for life?! Wuhhhhhhhhhhh? No way