I'd check out the hubs, if they're original (and that's a high possibility) they may be wearing pretty badly. Fronts are easy, slide on and off, but you need a BIG torque wrench to get the hub retaining bolt (buy new Motorcraft at the dealer, don't get the cheap autoparts store Dorman, it'll chew up your threads) to the 250lb/ft it needs.
Rears are tougher, they need pressed out and in. Take the knuckle off and have it done.
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.