Thanks for advice/info.
I don't have the Dash 8 yet so I don't know which version I'll be working with.
I'd prefer one of the later models with EOB or ERR but they don't come up often so I wanted to check the feasibility of upgrading an earlier model.
I have a TAS EOB board - thank you GRJ!. If the one I find has a SAW board, then hopefully the footprint will be the same. If not, it looks like ERR Cruise Commander is the answer.