To my knowledge, all of the traction lock cars are 8.8 (although I think the 7.5 prior to 86 might have also been traction lock). I'm a bit blurry about when the switch was made but gooch is correct about the 87-93. Particularly the GTs. I believe that the 7.5 was used up through 85. The 86+ GTs all had the 8.8.
You've got an 8.8. The only part I'm uncertain about is whether or not the LXs all had traction lock or not. I'm sure someone here can clear that up for ya.
86-93 actually. And just to clear things up for other people, the trac-lok started in either '83 or '84 and was used with the 7.5 up until 86 when they switched to 8.8.