I need help

[Foxlivesmatter]

I have a 91 notchback with 351w and a 4r70w trans. My problem is while driving when I get in to overdrive and I let off the gas pedal the rear end sways out kind of like a fish tail. I only notice it in overdrive Car alway drove straight even on hard pulls trying to figure it out cause I hate dealing with janky mechanics

 

[7991LXnSHO]

First things to check out are the control arms, bushings and the torque boxes.