So, to be better informed, one must understand how the LAU-138A/A cooled AIM-19L and AIM-9M. The physical conversion of LAU-7s to LAU-138s included the remove of the normal spun fiber liquid nitrogen bottles from the rear of the missile launcher. A smaller bottle was provided at the very front of the LAU-138A/As. Look at photos and see the nitrogen bottle at the front of the launcher. Easy to remove and replace regardless of particular weapon station. Nitrogen ran through a capillary into the missile to the seeker to supercool the IR sensor to make it very sensitive to any heat source.
