I am getting ready to order the new steel brake lines for my 69 project. When I went into the web site it looks like I can get factory style or stainless steel lines. What way should I go? I was told the stainless ones have a hard time sealing. Is this true? And the site also askes if I have 28 or 31 spline rear end. What difference would that make? I just want to order these right the first time. TIA