Garmin HRM 3-SS will connect/pair with forerunner 35 but will not show heart rate (see picture) - Accessories & Sensors - Running/Multisport - Garmin Forums
Garmin HRM-Pro™ | Heart Rate Monitor
Connecting Garmin HRM to Forerunner 35 - YouTube
Quick How-To: Garmin Wearable Heart Rate Broadcasting to Apps | DC Rainmaker