What year is your Redline? I'm having the same issue on my '04 and found GM changed a small clip for the cable on the rear axle half way through production in 2004 basically killing all chances of finding a new one now. I have the TSB hiding somewhere, it basically says to replace the entire rear axle assembly.
Havent found a replacement option yet so my drivers side is missing, but I'm really tempted to buy one for a 2005 from rock auto and just make it work.