We had a very hard time getting the front eye bolt out of our Mustang leaf springs when it came time to replace them . Here’s the tracks we used. Hope it helps!
https://www.superiormustangparts.com
Push-in style self-retaining threaded fasteners, called expansion nuts or snap-in nuts, are a type of self-retaining threaded nut. They are used throughout most industries where panels are assembled via mechanical fasteners.
For more information about Expansion nuts for industrial applications: https://www.araymond-industrial.com/solutions-standards