Mar-K offers the "tailgate link assembly" that you can also add to the tailgate to hold it from dropping when you unlatch it. The link folds into the tailgate end when you close the tailgate so it is hidden until you open the tailgate. It works a lot like a fleetside tailgate link system and is designed to work with the stock stepside tailgate. Click "parts and prices" and look at part #102835.
Mar-Ktech
