The part you want to take a pic of is where the electrical connector from the hub mounts to the bracket on the backside of the hub. If you have a 2001 and up GP you will most likely need the second design hub so in the BCA brand it will be the latter of the two part numbers (513179). In a nutshell the 2000 and under GP models have the stainless steel metal clip attached to the electrical connector from the hub. The second design uses the plastic thing.
For example my '97 GTP and wife's '99 Regal LS have the metal clip. My '01 Regal GS has the plastic so for this year I would need the second design hub.
The pic below is for example purposes but you can see the metal clip on the electrical connector from the hub wheel sensor which is applicable to 2000 and under.
BTW - The hub shown is an AC Delco which comes with the 3 hub bolts and a new axle nut.