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If your lines are 3/16", they will be a double flair with a 3/8"-24 thread size flair nut. If your lines are 1/4" the flair nut will be a 7/16"-24 size nut. The only place I can think that the flair nuts would be a different size at would be at the master cylinder. I haven't ran new lines to an ABS controller, so those could be a strange flair nut size like the master cylinders. GM didn't use metric lines on trucks till they went to the new body style Tahoe in 2006 & new body style truck in 2007.