This web site has lots of info. on the various options/part numbers/dash numbers for avionics.
Just click on their "INFO" button by a part listing.
Great if you are buying anything off E-Bay..... gil in Tucson
http://www.seaerospace.com/
Here is the KMA 20 info...
Doesn't seem like the KMA 20 has an intercom options...
KMA-20 Part Number Audio Panel Description
066-1024-03 Standard version with marker receiver/lights and lamp test
066-1024-04 International version with marker receiver/lights and lamp test
066-1024-05 International version with 2 ADF (no DME) selections, MKR and lamp test
066-1024-06 Beechcraft version without marker receiver/lights, with lamp test
066-1024-07 Beechcraft version with 2 ADF/no DME selections, no MKR, with lamp test
066-1024-08 Piper version with no DME, 1 ADF, COM1/COM2, 2 MIC selections only
066-1024-09 Piper version with no DME, 1 ADF, 4 position MIC select switch only
066-1024-10 Piper version w/ no DME, 1 ADF, 1 HF switch & pos. MIC select switch only
066-1024-11 Piper version w/ no DME, 2 ADF, No Auto, 5 position MIC select switch only
066-1024-12 Radio Telephone Version with AUTO and 4 position MIC select switch
066-1024-13 Piper version with 1 ADF, 4 position MIC select switch
066-1024-14 Piper version with 2 ADF, no DME, 4 position MIC select switch
066-1024-15 Standard version with red lighting and lamp test
066-1024-16 Standard version without marker beacon receiver and lights