IMO a sway control device should be part of every vehicle and trailer connection. A properly set-up vehicle/trailer combination shouldn't create sway under normal "loaded" conditions....., but not all towing conditions will be ideal (poor roads, winds, sudden maneuvers, etc.).
Bob
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2016 GM 2500HD 6.0L/4.10
2018 Jay Flight 24RBS
2002 GM 2500HD 6.0L/4:10 (retired)
2005 Jayco Eagle 278FBS (retired)
1999 Jayco Eagle 246FB (retired)
Reese HP Dual Cam (Strait-Line)