where is modprobe in Mavericks? I am unable to find modprobe in Mavericks.  Has it been removed?  Is it part of a package I haven't installed?
Could you explain what exactly you mean by "modprobe"?

The program usually referred to as "modprobe" is a Linux-specific program. It is not available for OS X, as it doesn't make any sense there.

If you want comparable functionality on OS X, you want to look at a program such as kextload instead.