rec.autos.simulators

What do you mean?  Are you asking where you get it from, or what you do
with it once you have it?

You can get it from Sierra's FTP site:
ftp://ftp.sierra.com/pub/sierra/patches/sports-sim/nas121.exe

Once you have it, run the self-extracting archive and place the
extracted files in your Nascar directory.  Then run the install file.
It's called something like patch.exe, install.exe, or setup.exe (I've
forgotten which).  It will then start to patch the game, overwriting
files as needed.

--

Emory University Graduate School of Arts & Sciences
Nascar Setups Page: http://www.racesimcentral.net/~ebusch/

where do I download the nas121.exe patch so that it properly overwrites
the appropriate files?

Where to get it .... http://theuspits.com/.  Go to the workshop and its
right there, along with Gerhard's track convertors and some other useful
utilities.  Eric already gave you the how to use it info.
/THansen