Are the lug nuts the same size? My truck is missing the jack and lug wrench. Just wondering if a half ton lug wrench would work?

GM standarizes there lug patterns on all models from 1500 to 3500 since 1999, they should have a 7/8 head with threads on the lug nut outer side and the thread pitch is the same, its a smart was of reducing production cost from making 3 lug nut sizes to only 1 size, cost effective and more convenient

You can also use the lug nuts from a later truck like Silverado or the new Subs/Tahoes.
The thread is the same, but you need a new wrench - they are 22mm. I put the new ones one mine, because i adapted the newer hub caps of a silverado to fit my Alcoa wheels.

Have a look :

http://www.dieselplace.com/forum/garageimage.php?do=full&p=51434&d=1200824225


Cu,
Sven