The part number you see on the channel card circuit board is not the part number for the channel card. It is the part number for the circuit board before any parts are installed.
There are 2 versions on the channel card.
If you look at your channel card you will see there are either 1 or 2 blue "boxes" on it.
If you see 1 Blue box your channel card has common Isolation - the part number is AV55M-A1
If you see 2 Blue boxes your channel card has individual isolation - the part number is AV55M-B1
