Rear brake question

Yes if anyone can tell me what years and what cars to get the brake assemblies that would be great. I know you all said c bodies, but all c bodies? From what years? Also for people that drilled there original drums, have you had any problems with cracking the metal between the holes that you drilled and the old holes? How long have you had this setup on your car? Of course drilling out the original brake drums sounds like the easiest option, but I plan of driving the car a lot on the street, and I also plan on it being at the dragstrip quite a lot as well, so I want to make sure it will hold up in the long run. Again thanks for your help.