Here is an interesting remark from a metalink forum:
From: Oracle, Dagmar Thompson 04-Sep-02 22:14
Subject: Re : Database links between Oracle 9.2 and 18.104.22.168.1
It is not a supported configuration. You need to be using at least 8.0.6 to be able to link between the two instance.
(end of remark).
Personally, I have not seen Oracle 7.3 for a decade or so I can’t take it any further.