The parity problem I think is because I use a 74 series parity generator, that he used. But i located it clear across the other side of the PCB, with its traces to the transceivers routed around all the other traces, from top to bottom multiple Vias. So, i may have to do a direct connect there.

I should have meandered the traces to make sure all the signals would reach the parity generator at the same time. Oh well.