I just put disc 2 into my retail xbox, it downloaded a TU for GTAV, the media id is 0C48794E. You could try uploading it manually to see if it works.
To upload, download the TU from the jqe website to your desktop, FTP to your xbox, goto
Hdd1Content0000000000000000545408A7 > create a folder called "000B0000", then put the TU in that folder, reboot xbox, should work.
PS. Don't post stuff asking for the same thing - you may get banned