Here's an interesting tidbit on Bil 5100's. I use them on the back of the Frontier, and I recco them. They come with a lifetime warranty. I could not source them locally so I bought them mail order.
One of them failed and spilled all it's oil past a blown seal. I contacted the online retailer and they said I would have to go thru Bilstein. I contacted Bilstein, and they said I would have to go thru the retailer.
Classic example of pointing fingers.
They are a good enough shock that I just went ahead and bit the bullet and bought another one to replace the bad one.
So at least in my case, their warranty wasn't worth the paper it's written on.
I'm going to try a set of KYB's next go 'round.