Someone please double-check me, but I believe the part he needs is DORMAN Part #905952. I don't have the proper GM part number, but this should be a good equivalent. $15 for one on RockAuto.com, maybe other online stores as well. Also, if that is a compression fitting holding two brake lines together in that picture, REPLACE THE LINE. Compression fittings aren't made to handle that amount of pressure...that moment you slam on the brakes because you REALLY need them, the fitting will burst. If you don't want to replace the whole line, at least bubble flare both ends of the line and use proper fittings and a union there.
