Bob's height adds a bit of a challenge to finding a pack. I'm 5'10" and most medium or large sizes fit me fine. I have several packs with non-adjustable suspensions that fit me well, but would not fit someone 5 inches taller than me. With a height of 6'3" my guess is Bob's height may rule out several brands. It's like looking for a pair of boots, buy the brand that fits best.