Bed Rail Length???

Hey all. I'm wanting to get some bed rails for my truck. What length do I need to get? I have a 98 Sonoma Extended cab w/ 3rd door, STEP bed. I measured it and I think it was 72" total, but the step part is a little higher than the rest....will that be a problem? Thanks

6ft sounds right. the step height shouldn't matter.

Sorry, forgot to mention I found a pair of used ones, that came off of another 98 Sonoma step bed. The part behind the bedside is that made the difference, and yes, these are shorter than that. They don't come up to it.