Originally Posted by
tdracer
Again, I don't know details, but what I remember is that it was much cheaper and easier to retrofit the -800 with the blended winglets than it was the -700 due to 'structural differences'.
I presume the issue must have been that the affected -800s were already built with the provisioned wing, while the -700s were the pre-modification unprovisioned wings. According to the winglet manufacturer 300 man-hours needed for a provisioned wing, 850-1200 for an unprovisioned wing.