Jesse Roth

Looking for some background info on this unit. All I know is that the American Wholesale Corporation filed for a trademark on this "Tote-A-Kar" wrecker tow sling style dolly in 1984. This unit looks like it was engineered to be stout but am not sure if there are helpful youtube videos anyone can point to that educates someone how to use this style correctly? Also, any ideas on what a unit like this is worth, ballpark? $700? $1.5k?