Hi bigwow,
I have found the free online help from the Raymarine website very helpful when I have wanted to "marry" various bits of Raymarine/Raytheon/Autohelm gear.
Give them all the info you can, particularly the serial number(s) and they promise to give you an answer in under 3 days.
I've used this service a dozen times and for each query have received clear answers to my questions
No connection, just a satisfied customer