how do i replace the radiant mesh part of my gas grill?

how do i replace the radiant mesh part of my gas grill? it is the part that holds the heat and glows red with the gas flame. the current one is old and has burned through in many places, resulting in spaces where toasting is innefficient. it seems easy to remove, but where can i find a replacement? do i need to salvage one and cut it to the shape/size i require? the unit is part of a sutter twin-hob/under grill/sink one-piece from the back of a trailer tent. thanks for your assistance