X84? You probably mean X86 as in IA32? 32-bit systems are no longer supported for new SAP installations. I guess you haven't kept up what SAP has been saying for years? I remember receiving a letter from SAP at least 3 years ago saying that support for 32-bit platforms is being phased out and everyone should be planning to migrate to 64-bit environments.
See the attached links for details.
https://service.sap.com/sap/support/notes/931024
https://service.sap.com/sap/support/notes/1560346
Anyway, according to the Agent Installation Strategy guide in SAP note 1365123 (attachment), your platform is still supported if you use the correct version of the Diagnostics Agent. In your case you should use Diagnostics Agent 7.3 SP02. The filename you should locate is
DIAGAGT73SP02_0-20006979.SAR
Uncar and install. See the attached link for details.