about shocks

I bought my truck (97 Z71 Ext Cab) about a year ago. It now has 144K miles on it (Highway Miles), and i am starting to notice a pretty bumpy ride. The shocks that are on it are yellow and say "Bilstien" on them. Could anyone tell me if these are original for that model. I don't have any way of knowing whether I should replace them or not. If they are original, I will definately replace them.

Yes Bilstein shocks came factory on all Z71's as far as I know. Thats why the ride is rougher than the 4x4 model.