The particular tanks in question were those manufactured by Allison Division of General Motors but reworked under separate contract by Airite Division of Sargent Industries. The two tanks, lightweight SWIP II models slated for LM-6 and subsequent vehicles, had suffered small cracks in the welds. So far, said Day, the weld process used in manufacture of the tanks was "highly suspect." Cryogenic proof-testing probably would be required to validate the tanks and to give confidence in the tank welds. Meantime, he said, the problem was receiving high-level attention both at Grumman and in Houston.