iPadOS 6.1.3 (build 10B329) is an official Apple over-the-air update for the iPad 4 (GSM). The update package is 18.2 MB. This is a delta (partial) update that requires 6.1.2 already installed. This update is no longer signed by Apple, meaning it can no longer be applied on-device through Settings.

Payload file: 341e8b021420405a42311b8a3f2cae617435bed2.zip.