Most likely its the axles end play is too much. Not so noticeable with floating OEM calipers. The rigid Wilwood (pistons on both sides of the caliper) gets the pistons pushed back when the axle shifts outbd.
These may help
https://www.ffcars.com/threads/c-cli...nators.637482/
https://nasaspeed.news/tech/brakes/p...o-do-about-it/
https://www.ffcars.com/threads/c-cli...n-diff.158342/