Should i quit farming Fastness?
Legendaries are hard to find in general. If you get REALLY lucky, you might find 1 in a day, even if you're farming Crawmerax pretty darn hard. The fastness isn't a bad place to farm, but for better lewt, I'd say play Knoxx. I know a few folks farm the Prison with soldiers since they're either locked out of the Armory, or can't fight Crawmerax.
You might want to just see what folks have to trade. A lot of collectors tend to hold onto good weaponry in case they run into someone who needs a really awesome gun that they themselves don't need. I tend to collect a lot of Machine Guns just off of that thought.
So yeah, just an FYI.
Thanks guys, i've got about 65 legendaries all from fastness. The highest level weapon i got from there so far is 52 though. Its loaded with legends, i must have gotten rid of about 20 to 30 others to make room in my inventory and the bank. Maybe i'll find the ones im still looking for in knoxx.

Forget about everything but Knoxx... The Armory and Crawmerax are what you are looking for, specially with your Level...
Time Spent on Borderlands : 1700 Hours +