RepairPal Certified shops can diagnose and repair your 2002 Mazda Tribute. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
Can't answer without knowing -1)skill level , 2) tools available , 3)location of converter , 4) amount of rust involved, 5)work environment(shop/lift or garage floor/driveway?
The guy doing the work is a mobile mechanic. I assume he has the necessary tools and lift capabilities at his home shop.