LNG-TU-15-38 Compression Tester Adapter for GM Duramax 6.6L Turbo (M10x1.25 mm) Features: Compatibility-- Diesel Compression Test Adapt Adapter uses with STAR Diesel Compression Tester TU-15. Compatible with GM: Duramax 6.6L Turbo Diesel (2005-present). Also works on a Duramax LML engine. Nice Design-- M10-1.25 thread adapter with quick disconnect screws into the head of the engine in the glow plug hole. Manufactured to specific thread tolerance standards. Easy to Use-- Simply plug right into the back of the gauge. Thread the adapter into the glow plug hole and then it’s like a quick release that goes on the back of the adapter which then goes up to our gauge. .