XT skewer 178mm - does it exist?

I always knew the XT skewer that came with my rear XT hub wasn't really long enough, but today, it agreed with me as the threads stripped off the end. LBS had a 173mm version in stock. By comparison, mine was a 168mm. But the Shimano packaging has a 178mm length option indicated. Since I'm kind of a Clyde (6'4", 250), and have already had a failure, I'd like to make it bomb proof when I spend money. All the skewer listings I can find indicate 135mm for the inside of the dropouts, which is useless information to me.

Anybody know whether the 178 length on the packaging even applies to the XT or XTR line, and where I might be able to get one if it does?

Thanks!