Since it's running after an index rebuild, you only need to update column statistics, not index statistics.
Shouldn't be running that long, I've had TB size databases where the stats update takes maybe an hour. Are you hitting IO bottlenecks perhaps?
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability