You can get all versions of expander from our website:
https://opensprinkler.com/product/zone-expander/
On v2 there is no jumper for addressing because it uses shift register cascading, so the order of zones is completely determined by the order the expanders are linked.
V3 uses I2C IO expanders because ESP8266 does not have enough GPIO pins to talk to shift registers and I2C is the most efficient way to support expanders using only 2 signal lines.