what thickness synthetic winch line for a 12K winch?

[bas157]

Anyone know what thickness (diameter) a synthetic winch line should be for a 12,000 pound winch? I'm hoping to pick up a Warn 12K winch tomorrow but it apparently has a fray in the line somewhere. I might just shorten the line depending on where the fray is, but if I've gotta replace it, I might look into a synthetic line.
Any sponsors here have really good deal on synthetic lines?

thanks
Bruce