I want to know which side of a ct is the line and which side is the load on a 400 amp meter pan

Ask your foreman, supervisor or boss.
This is not something you should even be touching if you don't know what you are doing.
This is also way beyond anything DIY.

Doesn't your power company have rules regarding who works on things like this?
Things like diagrams for meter pans and CT cabinets are typically in the utility's rule book.