I think that Oracle.o is built in the 'perl Makefile.PL' step of building the dbd. Yeah, it is AIX5.1, trying to make everything full 64bit. The compiler is the latest Visual Age C++ from ibm. Thanks! I got this to work...fyi:

Using Oracle dbd 1.16
Perl 5.8.4 built like this, with Visual Age 6.0:
config_args='-Dcc=xlc_r -Dusenm -Dprefix=/appl/datasync/work/perl5 -Dusethreads -Duse64bitall -des'
==============================================
Used DBI 1.42
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Added this to top of Oracle.h:
#define A_OSF
#include <oratypes.h>
=======================
Set LIBPATH to point to 64bit Oracle libs first.
export LIBPATH=$ORACLE_HOME/lib:$ORACLE_HOME/lib32:/usr/lib
Use: perl Makefile.PL -nob
Change all references in Makefile of LD_RUN_PATH to be LIBPATH.
Change nothing else, left all flags in Makefile, including -q64.
Passed make, and all tests.