Hi Steve,
I received the new display just now.
It is equipped with the PCF 8574T.
It is connected to the QC2004A display in the following way:

pin_4 p0 > RS
pin_5 p1 > RW
pin_6 p2 > enable
pin_7 p3 > Backlight
pin_9 p4> data4
pin_10 p5 > data5
pin_11 p6 > data6
pin_12 p7 > data7

It is different wrt the one I had before: it has a different connections between the PCF and the LCD.
I will be ready for testing tomorrow or monday: please suggest me what trials to do just to start.
Thanks for all
Ambrogio