Early TJs used thin sheet metal to support the gas tank and it was vulnerable to trail damage. At some point, that sheet metal became substantially heavier and turned into a pretty fair skidplate. I'm not sure when that happened but maybe around the 2000-2001 time frame. So that just means I'd definitely avoid 97-99 but I'm not sure after that exactly what year the change occurred. As I think more about it, that beefier skidplate may have been introduced as late as 2003.