I know it's been over five years, but I don't think it hurts to provide an answer. There's no "custom made" horn for the DD35A. However, I would highly recommend the Leslie S5TRRO or the S3L horn (specifically the ones by therock) as both of the horns were used on the DD35A units. The horns can be found on the download station and can be added in by editing the config file and replacing the old kuid with the new one next to the words "hornsound."
