This object is ** NOT ** created by default in 8i databases :

SQL*Plus: Release 3.3.4.0.0 - Production on Thu Feb 28
15:06:15 2002

Copyright (c) Oracle Corporation 1979, 1996. All rights reserved.


Conectado a:
Personal Oracle7 Release 7.3.4.0.0 - Production
With the distributed, replication and parallel query options
PL/SQL Release 2.3.4.0.0 - Production

sys@po7:SQL> desc sys.x$kcbrbh
Name Null? Type
------------------------------- -------- ----
ADDR RAW(4)
INDX NUMBER
COUNT NUMBER
............

SQL*Plus: Release 8.1.7.0.0 - Production on Qui Fev 28 15:06:35 2002

(c) Copyright 2000 Oracle Corporation. All rights reserved.


Conectado a:
Personal Oracle8i Release 8.1.7.0.0 - Production
With the Partitioning option
JServer Release 8.1.7.0.0 - Production

sys@po8i:SQL> desc sys.x$kcbrbh
ERROR:
ORA-04043: o objeto sys.x$kcbrbh não existe

--->> EXACTLY what you want to do here ?