I bought a Largr to replace the Medium yoke that came with my second hand 3DAP. The back of the replacement harness ended up being about 3 or 4 inches longer than the one I had. It was only fabric that was longer and not the plastic sheet so it was a cheap task for my local tailor. Overall it was a great upgrade for me and the pack has a newfound level of comfort for me. The straps are a touch longer as is the length of the wider shoulder portion. It rides way better over my shoulders and truly reduces fatigue with light and heavy loads compared to the stock medium harness. I can now carry more weight for longer without feeling shoulder fatigue. Worth it is you are finding that the medium is just not working for you in the stock config.