I've only seen them on Canadian spec trucks, however I believe they were installed around 1982 model year. They are hard to come by. do you have the inner part and just need the outer shield? They become brittle and break on the trail all the time. You'd be better off making a louvred piece of aluminum to keep the water out.
Thanks guys for your reply... yea I would like to find the inner and outer parts including rubber gasket but I think Stump had a great idear ! might as well make the outer parts at lease till I find some original.