Here's what I did with my '53 box. The Gaylord Lids cover is fibreglas with 2 air struts and locks. Very happy with it. Almost 6 years old on my daily driver and still perfect. Watertight. I bought mine in primer and had it sprayed satin black. Here's a link to the company's page: http://www.gaylordslids.com/showroom/showroom/chevy-gmc-1947-1953-stepside-short-bed/ Cheers.
