OEM Victor Reinz 12 mm X 100 mm XZN 12 Point Cylinder Head Bolt for 1978 - 1985 Mercedes 240D, 300CD, 300D, 300SD and 300TD, 615 990 01 12
"Using new head bolts when performing a cylinder head installation is always a good idea however, on late-model engines that came from the factory with TTY (torque-to yield) head bolts, replacement is an absolute necessity. TTY bolts are designed to exert the maximum clamping force for a tight head gasket seal, however they permanently stretch and could fail if re-used."
This is an M12 X 1.75 X 100 mm 12 point XZN later style cylinder head bolt.
These will fit select models of the 1978 thru 1985 Mercedes 240D & 300D diesel engines, PLEASE see the application fitment table to verify fit and quantity used.