Just picked up a 1993 tc- cat. converter shields?

Hi, i just got a 93 tc for hubby after his car was totalled. There was a rattle underneath which he quickly tracked to the heat shields on the cat.con. One was rusted off , the other already clamped on to "fix". Must the entire cc be replaced to fix this and any cost est. to have it done? How hard for the "normal" household car repairman to do it or should he have it done. Thanks for the help.