When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The "20" is the pitch of the thread. It's a 1/2"-20 thread. My truck is a d250. Same as yours, but 2 wheel drive. I have 8 bolt wheels as well, meaning 32 lug nuts total. As long as you get lug nuts that have the same size thread, you can use whatever size hex you want. Stock is 13/16" I think.