if you want true duals you need a double hump transmission crossmember to clear the pipe. any 79-93 off road/cat'ed h pipe will work. flowmaster american thunder stuff is pretty popular. you will need an extra exhaust hanger on the side without a tail pipe.

chad at blueoval corral can help you, 727-571-1996
joe at fordspeed can also help you, 727-549-8255

there are other shops that i understand treat cusomers fair, im sure they'll chime in, you can save big on barley used parts at these shops sometimes, or check domestic car parts for sale.