API C MountJournal.GetMountInfo

Returns information about the specified mount. creatureName, spellID, icon, active, isUsable, sourceType, isFavorite, isFactionSpecific, faction, hideOnChar, isCollected = C_MountJournal.GetMountInfo(index)

• index : number - the index of the mount, in the range of 1 to (inclusive)

Returns nothing if the specified index is out of bounds.

Current values of the return include:

• 0 - not categorized; includes many mounts that should (and may eventually) be included in one of the other categories
• 1 - Drop
• 2 - Quest
• 3 - Vendor
• 4 - Profession
• 5 - Pet Battle; currently includes only Felsteed, which is learned by warlocks at level 20 and is probably mis-flagged
• 6 - Achievement
• 7 - World Event; currently includes only Swift Lovebird
• 8 - Promotion; currently includes only:
• Big Blizzard Bear from BlizzCon 2007
• Dread Raven from the Warlords of Draenor Collector's Edition
• Hearthsteed from the Hearthstone release promotion
• Imperial Quilen from the Mists of Pandaria Collector's Edition
• Ruby Panther, which is crafted by Jewelcrafting and is probably mis-flagged
• Spectral Gryphon from the Scroll of Resurrection promotion
• Tyrael's Charger from the 2011‑2012 Annual Pass promotion
• 9 - Trading Card Game
• 10 - Blizzard Pet Store

These are the same source type IDs and labels used in the pet journal.