A common complaint in late-model Chrysler rear-wheel-drive units is a cracked and/or leaking case caused by installing the cooler lines. The tapered threads and the lack of a stop on the OE cooler line fitting can load the case and create a fracture, resulting in leakage that may require replacing the case. Sonnax cooler line adapter 22000-01 seals on the leading edge, preventing fluid from reaching the fitting threads and crack. The fitting has straight, not tapered threads to prevent the crack from spreading. The Sonnax adapter allows case salvage without transmission removal.