This linksys was easy to work with. In general Linksys makes it easy unlike Asus.
I figured out where to add the serial connector.
Here is a close up
When I opened it up I surprised at how small the board was, a little bit of research showed me that this unit has 8MB of flash vs the 4MB on a version 1 board.
There is a weird issue where the br0 gets disconnected from vlan1 so you have to manually add it either through the serial console or the wifi connection.
Kind of nice mod, I want to find more of these.