Has anyone have a fix for the heater water tubes under the cat that keep leaking?

I only had 1 that leaked and that was because the plug at the rear of the right side tube had been loosened or came loose on its own. Where are yours leaking?

The lager HEATER tube is leaking about 6 in. from the front connection. It is coming from corosion in side the tube. Have replaced them one time with used ones and now the t have a pin hole in it.. Would likw to have a new set..