Lexs400

I'd like to know if someone has the part # for the check valve that sits between the master cylinder and the vacuum module.
this is for a 93 ls400 with traction.


More over is there a website one can look at the diagrams for the system like the dealership service centers do ?
Most of the time it's a pain to explain to the parts dept as to what we're looking for. A pic would prove to be a thousand words at that point.