did you use ufsdump to clone these? or maybe forget to do the installboot once you were done? I have forgotten the installboot too many times to count
so basically mount the new drive on /mnt or wherever
cd /mnt
ufsdump 0f - / | ufsrestore rf - .
i would say use installboot, but i didnt see you were running x86 until a second ago but installgrub should work. I have never tried it, i only use sparc and installboot is still a part of the release up to the current u9.
hope this helps get you going