The engines were assembled at Cleveland as mentioned, trained to Milpitas. Similar to the sheet metal. The cars, roller and drivetrain were assembled at the San Jose plant and trucked to SAI. I have not heard nor not heard of a holding area (?).
However I do know that 38 cars arrived in one day, which was statistically singular, with the dated components as noted. McNamara’s protégés were efficient, however I remain impressed, logistically, that an engine assembled on the 28th In Ohio, trained, accepted, sorted, installed, thence trucked was on property at LAX on the 9th.