like every gmt400, the oil cooler lines start to leak eventually at the hose metal crimp, which mine are doing. searching for a suitable replacement that never needs to be replaced again doesnt really exist unless you make it your self. At work i have access to all the stainless steel tubing and swagelok fittings i could think of. before i go trying make my lines, would a solid tube have routing issues trying to get it in place, id love to eliminate the hose part of the line which seems to be the weak link.