A tailgate lift assist counterbalancing hinge assembly that can be retrofitted to the exterior of a vehicle's tailgate is disclosed. The hinge assembly includes first and second tailgate brackets for attaching the hinge assembly to the exterior of tailgate. The first tailgate bracket includes a perpendicularly bent flange to facilitate attachment of the bracket to the tailgate. The hinge assembly also includes a torque rod with a bend to facilitate access to a fastener used to attach the first tailgate bracket through the bent flange to the exterior of the tailgate. A retainer block, which is positioned on a flange of the second tailgate bracket, is secured with the bracket to the exterior of tailgate using a second fastener. The torque rod extends on the exterior of the tailgate between the first and second tailgate brackets.