Hi Swizzle-
Coot's lures makes a rattling crawler harness. You can see a photo of it on their website.(www.cootslures.com)
I find components at Stamina, Inc, Jann's Netcraft, Barlow's Tackle Shop, and Moore's Lures.
The fluorocarbon line I've been using is Berkley Vanish.
Oh, by the way, welcome to our addiction!