dbms_space.free_space[13]

create or replace procedure show_space
( p_segname in varchar2,
  p_owner   in varchar2 default user,
  p_type    in varchar2 default 'table',
  p_partition in varchar2 default null )
-- this procedure uses authid current user so it can query dba_*
-- views using privileges from a role and so it can be installed
-- once per database, instead of once per user that wanted to use it
authid current_user
as
    l_free_blks                 number;
    l_total_blocks              number;
    l_total_bytes               number;
    l_unused_blocks             number;
    l_unused_bytes              number;
    l_lastusedextfileid         number;
    l_lastusedextblockid        number;
    l_last_used_block           number;
    l_segment_space_mgmt        varchar2(255);
    l_unformatted_blocks number;
    l_unformatted_bytes number;
    l_fs1_blocks number; l_fs1_bytes number;
    l_fs2_blocks number; l_fs2_bytes number;
    l_fs3_blocks number; l_fs3_bytes number;
    l_fs4_blocks number; l_fs4_bytes number;
    l_full_blocks number; l_full_bytes number;

    -- inline procedure to print out numbers nicely formatted
    -- with a simple label
    procedure p( p_label in varchar2, p_num in number )
    is
    begin
        dbms_output.put_line( rpad(p_label,40,'.') ||
                              to_char(p_num,'999,999,999,999') );
    end;
begin
   -- this query is executed dynamically in order to allow this procedure
   -- to be created by a user who has access to dba_segments/tablespaces
   -- via a role as is customary.
   -- note: at runtime, the invoker must have access to these two
   -- views!
   -- this query determines if the object is a assm object or not
   begin
      execute immediate
          'select ts.segment_space_management
             from dba_segments seg, dba_tablespaces ts
            where seg.segment_name      = :p_segname
              and (:p_partition is null or
                  seg.partition_name = :p_partition)
              and seg.owner = :p_owner
              and seg.tablespace_name = ts.tablespace_name'
             into l_segment_space_mgmt
            using p_segname, p_partition, p_partition, p_owner;
   exception
       when too_many_rows then
          dbms_output.put_line
          ( 'this must be a partitioned table, use p_partition => ');
          return;
   end;


   -- if the object is in an assm tablespace, we must use this api
   -- call to get space information, else we use the free_blocks
   -- api for the user managed segments
   if l_segment_space_mgmt = 'auto'
   then
     dbms_space.space_usage
     ( p_owner, p_segname, p_type, l_unformatted_blocks,
       l_unformatted_bytes, l_fs1_blocks, l_fs1_bytes,
       l_fs2_blocks, l_fs2_bytes, l_fs3_blocks, l_fs3_bytes,
       l_fs4_blocks, l_fs4_bytes, l_full_blocks, l_full_bytes, p_partition);

     p( 'unformatted blocks ', l_unformatted_blocks );
     p( 'fs1 blocks (0-25)  ', l_fs1_blocks );
     p( 'fs2 blocks (25-50) ', l_fs2_blocks );
     p( 'fs3 blocks (50-75) ', l_fs3_blocks );
     p( 'fs4 blocks (75-100)', l_fs4_blocks );
     p( 'full blocks        ', l_full_blocks );
  else
     dbms_space.free_blocks(
       segment_owner     => p_owner,
       segment_name      => p_segname,
       segment_type      => p_type,
       freelist_group_id => 0,
       free_blks         => l_free_blks);

     p( 'free blocks', l_free_blks );
  end if;

  -- and then the unused space api call to get the rest of the
  -- information
  dbms_space.unused_space
  ( segment_owner     => p_owner,
    segment_name      => p_segname,
    segment_type      => p_type,
    partition_name    => p_partition,
    total_blocks      => l_total_blocks,
    total_bytes       => l_total_bytes,
    unused_blocks     => l_unused_blocks,
    unused_bytes      => l_unused_bytes,
    last_used_extent_file_id => l_lastusedextfileid,
    last_used_extent_block_id => l_lastusedextblockid,
    last_used_block => l_last_used_block );

    p( 'total blocks', l_total_blocks );
    p( 'total bytes', l_total_bytes );
    p( 'total mbytes', trunc(l_total_bytes/1024/1024) );
    p( 'unused blocks', l_unused_blocks );
    p( 'unused bytes', l_unused_bytes );
    p( 'last used ext fileid', l_lastusedextfileid );
    p( 'last used ext blockid', l_lastusedextblockid );
    p( 'last used block', l_last_used_block );
end;
/


try that one, you must be in 9i using assm with the older version from 8i -- 
assm does not have freelists