If by "Mossback" you mean the old Klamath steelhead fly (and being from Redding, I guess that's a fair bet), the pattern is the same as the Brindle Bug (e.g. http://www.westfly.com/patterns/stee...indlebug.shtml) but uses green/black variegated chenille instead of yellow/black. If you want a bead head version, just add a gold bead of the appropriate size, and some like to add a little krystal flash to the wing. For the Klamath, I fish #10-8's tied on a standard 1x nymph hook like the TMC3761. Doug's Bugs makes a chenille with a little flash mixed in that makes a particularly nice body, and it is even labeled "Mossback," so you might want to look around for some.