Just returned home with my new-to-me 336. It has a Loran-C, model 120MC by STS Avionic Products. Have searched the web for this outfit to get an update in the memory, but have had no luck in finding this group. They are/were located in St. Louis, MO. Does anyone out there know if this place is still in existence? Or of anyplace that may be able to help me update this receiver? Thanks to all that answer.