It sounds a little like you may be using the wrong size pack. I think you’re trying to find a pack by asking the wrong question.

Have you been to an outdoor store (REI or a local hiking store) to be fitted for a pack? From your reply to my post, it sounds like you’re shopping for the length of a frame, but all the measurements given in catalogs are for TORSO length, not frame length. The torso length measures the length of the suspension (hip belt to top of shoulder straps.)

At 5’11”, (29” inseam), I’m between a 20 and 21 inch torso length. I just walked out and measured the length of the frame on my pack, and it’s just over 25” long. If I look on a website, the size L I use is listed as fitting 20-23” torsos. (The M is described as 19-21” torso, but the L fits me better.)

I think you’re making an apples-to-oranges comparison; go to a backpacking store and have them measure your torso length. While you’re there, you can try on various packs and see how they feel.