if it is like the 94/95 gt it is the heater cross over pipe I think it is called that goes to the heater core and back. Hopefully it is not like the 94/95 that is specific for that model year, known to leak at the orings and has never been reproduced. Now you can replace the orings on those pipes by carefully crimping the end so that the screw caps can come off and gain access to the orings to replace them. That and a new coat of paint is about as much as you can hope for on the 94/95 gt....