Where can I find a speedometer for a 1987 379 Peterbilt?

and is it the seedometer or could it be something else.|||Order it from the dealer, ebay or use a aftermarket one. And if your a trucker I pray for you, not many people see how much you help people. Thanks.|||try thepartsbin.com or your local garage, these parts are very hard to find. you might as well look for alternative parts from other makes that you can use.