Also, if you have login access to Sunsolve,
please review the details inside Spectrum Infodoc 76028.
"Why are there multiple kernel patches for the Solaris[TM] 8, 9 and 10 Operating Systems?"
Essentially it says that as each kernel patch became large,
it was supplanted by a new patch with a new number.
When that became large, in turn, another new patch was created.
The best way to get your Operating Environment patched is to use
the full Recommended Patch Cluster.It has everything and
patches will get installed as you system might need them.