Weld in Catalytic Converters replacement

Hello, Im not interested in replacing the entire exhaust system. Im having no issues with my exhaust system coolant heater and I have the capability to weld in new catalytics my self. I was wondering if any one knows the length of the catalytics and the exhaust pipe diameters so I can get this ordered? Also I couldn't find the information so Im not really sure but is one of these (picture attached) a resignator and not a catalytic?

Sorry I would get these dimensions my self but Im deployed and would like to get this parts ready for me when I return home.