Based on what I've seen, the LSD is a fairly rare option on non SuperCoupe Thunderbirds. It was an option, and some folks got it, but most didn't. It wasn't part of the sport appearance package, or any other "package" option group that I'm aware of, so either they checked the box or they didn't.
SC's were more common with them as they were the "performance" line. Fairly certain the ABS/Traction Control equipped models did not have track lock as they relied on the traction control to take it's place.
97 Thunderbird LX (The GT Bird)
PI Swapped NPI motor with some port work on the heads, PI cams, 80mm MAF, CAI that feeds from fenderwell. Jmod, 3.73:1 TL in Mark VIII carrier, Mark VIII aluminum LCAs, 93 Mark VIII driveshaft, PBR brakes (soon to be Cobras), 18x9 wheels, 255/40/ZR18 Tires, Front and Rear strut/shock bracing, GR-2 shocks, Eibach 1.5" springs, 1989 SC front and rear sway bars.