It should be 3/16 I think. It's a standand size brake line anyway. Just buy a tube bender and bend it yourself; it's easy. The tube benders are under $10. Remove the old brake line without bending it too much. Take a piece of stiff wire and mold it to the shape of the old line, then straigten it out and measure how long it is. Go buy a brake line that is the same (or closest) length. Start with your new tubing bender; it doesnt have to be perfect.
Don't put the brake line back in the metal retainer clip above the diffy. The clip retains moisture betweem it and the brake line and rusts out the brake line in that area. Ty-wrap it to the back of that clip and then spray it with oil to prevent rust.
