For SQL Server 2005, the syntax would be:

select record_count / page_count

from sys.dm_db_index_physical_stats(392, 1598628738, null, Null, 'DETAILED')

where index_level = 0

The details are given in the same article as to its components.

The article also gives details on the equivalent SQL Server 2000 option.

Usage of "physloc" is specific to SQL Server 2008 as mentioned in the article.