What version of Solaris is it?
On my Solaris 9 or older, the file should be in [tt]/etc/init.d/xntpd[/tt]. And there should be a hard link [tt]/etc/rc2.d/S74xntpd[/tt].
If it's Solaris 10, it's managed by the service management facility (smf) under the service identifier [tt]svc:/network/ntp:default[/tt]. Type [tt]svcs[/tt] to see if it's there.