rctrucker2, they are definitely button head socket cap screws, and stainless, at that. You'll need a variety of lengths for a Tamiya truck. Best to take a look at the manual and see what lengths are necessary. If you don't have a manual for your truck, you can find one online.
http://www.tamiyausa.com/items/radio-control-kits-30
I don't know about everyone else, but I order all my screws from McMaster-Carr.
www.mcmaster.com