Brake Hoses, Lines/piping, And Fittings problems of the 2002 Chevrolet C3500

Husband performed oil change on truck. Truck is driven infrequently, only used for towing my horse trailer, so oil is only changed about once a year, and truck is garage kept. When underneath truck, husband noticed that all brake lines feeding into the abs unit are severely corroded and could fail at any time. Based on condition of brake lines, husband (a mechanic) feels abs unit is probably full of rust as well. Entire braking system may be compromised and full of rust. Truck will not be safe to drive until brake lines are replaced, and potentially entire braking system is overhauled. Called dealership, they refused to do anything because the truck is out of warranty. We have contacted Chevrolet directly and are awaiting a return phone call. My husband has 30 and 40 year old cars at home that have cleaner original brake lines than our 10 year old truck does.