I tow my A Frame with 2018 Toyota 4runner SR5. The Owner's manuals of earlier 4runners acknowledged that the factory installed receiver assembly was suitable for use with a Weight Distribution System (WDS). The 2018 Manual is silent about WDSs. It took 6 or 8 phone calls and 4 emails to Toyota Customer Service to get a response from Toyota stating that the factory installed receiver assembly on the 4runner was suitable for use with a WDS (Toyota Incident #: 160908-000240) as long as the towed weight is not more than 5000#.