How to fetch Package DDL in Oracle 8i I want to fetch a Package DDL in Oracle 8i.

8i doesn't support DBMS_METADATA.get_ddl.

Can it be done using export?
DBMS_METADATA.GET_DDL is not mandatory to view the source of a package.

You can use DBA_SOURCE/ALL_SOURCE: https://docs.oracle.com/cd/A87860_01/doc/server.817/a76961/ch277.htm#101236

select text from dba_source
where owner = 'OWNER_OF_PACKAGE'
and name = 'NAME_OF_PACKAGE' order by type, line;