Here is a quick access list for all available Tech Briefs.
AP4: https://catalog.pac-audio.com/index.php?controller=attachment&id_attachment=1809
GMRVD - (Retaining 3rd row display in GM vehicles)
Link: https://catalog.pac-audio.com/index.php?controller=attachment&id_attachment=48
GMRVD2 - (Retaining 3rd row display in GM vehicles)
Link: https://catalog.pac-audio.com/index.php?controller=attachment&id_attachment=1828
Any RSTX / RP5 / OS Module - (Accessory shutdown at high volume)
Link: https://catalog.pac-audio.com/index.php?controller=attachment&id_attachment=1773
C2R-FRD1 - 1 (Factory Amplified System Shutting Down/Resetting) 2 (Powering up the mid line amplifier in 2009 Ford/Lincoln/Mercury vehicles)
Link 1: https://catalog.pac-audio.com/index.php?controller=attachment&id_attachment=829
Link 2: https://catalog.pac-audio.com/index.php?controller=attachment&id_attachment=26
RPK5-GM4101 - (HVAC Controls Inoperable)
Link: https://catalog.pac-audio.com/index.php?controller=attachment&id_attachment=943
RPK5-GM4102 - (Proper installation of center inserts of RPA-KNOB1)
Link: https://catalog.pac-audio.com/index.php?controller=attachment&id_attachment=1623
RPK4-FD2201 - (No reverse camera image after installing the CAM-FD21 harness)
Link: https://catalog.pac-audio.com/index.php?controller=attachment&id_attachment=1851
RPK4-FD2101 - (Outlines how to pin wires in harness to power up factory USB Hub in center console)
Link: https://catalog.pac-audio.com/index.php?controller=attachment&id_attachment=1806
RPK4-HD1101 - (Intermittent steering wheel button functionality)
Link: https://catalog.pac-audio.com/index.php?controller=attachment&id_attachment=982