I have 3 machines with 32-bit windows 2003 but I can't find an agent (Universal Forwarder)
What I can do?
Upgrade the 3 machines. Windows 2003 is not supported and neither is the version of UF that used to run on it. Even if you find a copy of the UF it won't be compatible with modern versions of Splunk.
Depending on what data you want to get off the machines, you may be able to use Windows Event Forwarding to send the event logs to a newer machine with a working UF.
Upgrade the 3 machines. Windows 2003 is not supported and neither is the version of UF that used to run on it. Even if you find a copy of the UF it won't be compatible with modern versions of Splunk.
Depending on what data you want to get off the machines, you may be able to use Windows Event Forwarding to send the event logs to a newer machine with a working UF.