Classic/Antique Car Repair: 1968 Chevrolet P/U front drum brakes, stock drums, rear drums

Question
I have a 1968 Chevrolet 1/2 ton pick up. I wanted to do the brakes, so I ordered front and rear drums and shoes. Much to my surprise, when I pulled the front wheel off, I discovered that the front drum seems to be riveted to the hub. The stock drums I purchased are the same size - do I just need to buy hubs as well? This seems odd to me.

Now, I don't know how to proceed, or if my truck had been modified by the previous owner. I wanted to just cut the rivets off, but...Any ideas?

Answer
Cut the rivets and install the new drums. make sure that they fit the hub snugly as this is what centers them. Some drums were riveted and others used a special tool that pressed the lug studs through the hub and drum and then swedged them in place. The rivet serve no purpose once the wheel is torqued in place as the drum is sandwiched between the wheel and the hub. The rivets and other methods mentioned keep the drum in place should the wheel come off.
Brad