I go over the best practice for soldering your radio harness the right way. Also I show the differences in the Metra Wiring Harness Adapters for your Fox Body Mustang Head Unit Installation.
Links-
www.417fox.com
Crutchfield Link -
https://www.crutchfield.com/p_120705006/Metra-70-5006-Receiver-Wiring-Harness.html?tp=2977