I don't think that the Total Chaos shackles are available any longer, not positive on that, but I do remember a blurb about that somewhere. I have them and the comparison between them and the stockers is night and day!!! Yes, they lower the rear 3/4" but to be honest, you can't even tell a difference.
Greg's site,
www.prgproducts.com , simply says PRG Shackles--Coming Soon!, which it probably has for awhile now. I haven't seen him post anything that said that they are available yet though????? Best bet is to give him a call if you want a set of beefier replacements.
You're not the first to have this happen though. And it SHOULD be covered on the 60k warranty!!!
The stock shackles can be welded to make them stronger, so I'd suggest if it's not covered under warranty, buy a replacement, weld it, then take the other side off and weld it up too!!
Here is a picture of the TC shackles:
