One problem related to brake hoses, lines/piping, and fittings has been reported for the 1998 GMC Yukon. The most recently reported issues are listed below.
Bumper to bumper traffic during rush hour, brakes went to the floor causing about a 10 mph impact into pickup in front of us. Glad we weren't up to speed when the brakes went. Upon further inspection, I have rusted brake lines, and the front crossover line leaking profusely due to corrosion of metal.