GM-50717-20 includes adapters to use with GM-50717 Valve Spring Compressor. Many new engines use M5 fasteners to retain cam carriers or camshaft covers to the cylinder head, and the 3.0L Diesel (RPO LM2) is an inline 6-cylinder with a cylinder head longer than most previous GM engines.
GM-50717-20 includes the bases to span the width of the new cylinder heads, M5 fasteners, and longer rods required for the inline 6-cylinder head, but can also be used on other new GM engines.