Hi yuk15,
Well its not the module - but the antenna - of which they are on back order. so be prepared to wait. Apparently its a big issue because they dont have enough, and if you have a painted one - they are shipped without paint and then painted. So if it is the module, then 1 week and $1000 on warranty, but GM backed out when they did more diagnostics and found it was the antenna.
Me - Well I drove my truck for two weeks, gave it back to them when Onstar went down, I got an Enlcave for one week (yuk) and now I have a loaded Yukon as my loaner. I certainly cant complain, dealer has kept me in the loop as far as parts and whats going on and I m driving a loaded Yukon. Be prepared for a wait tho - it took GM a week to figure out it wasnt the module and no ETA on parts.