Larry, Did any of your existing pipes have the crimps in the pipes as were typical to chambered? Is your car's build date 05A or before, and before the cut off date of May 19th? The other possibility, to determine yes or no, would be finding the firewall chalk writing by fisher body, indicating N10 for deep tone mufflers!
Gary, WOW!, Did Eric indicate any specifics on dimensions of the mounting hole locations for the hangars that are above the axle? I thought they were in the same spot for either N10 or NC8. If they are different, looks to me like that would pin point which system you had, if you didn't know! Those hangar locations, and the firewall writing may be the only clues some people will have!
THANKS,
Bryan