Will I need a "sway control unit" if I was using my Blazer to flat tow a car? Or is it just needed it I was towing a trailer? Thanks.

 

I have towed with a homemade tow bar
My mistake was I tied off the steering wheel , found out the first turn that was not right
I would compare using a tow bar to towing a hay wagon
Unless your towing with something larger like a motorhome I would not recommend for long distance or high speed
A car trailer will be a better option plus you gain braking power
Not all trailers use or need sway control , just makes things better
I think some tow bars have sway control built in