You also can't go by the pictures on the case anymore. I know many websites published pictures of the cases marking the differences between the old and the new versions. How ever, I have verified that R* is now selling new versions of GTA:LCS with the old case, probably to try to take advantage of the fact that GTA:LCS in the old cases are selling like hotcakes. :mad1:
If it's new, it's the new version regardless of the case. You're only bet now is either ebay, or go find an old copy at a rental place (if you live in a big enough city).