According to the FCC filling, The LG D631 as a 145.22 mm display which corresponds to a 5.7-inch display.
This model number LG-D631 was first spotted in late March in a leaked document, which reveals that the code name of LG-D631 is B1lite. It is believed that the LG-D631 is AT&T version of the G pro 2 lite.
Below is rumored AT & T LG D631 Specs:
OS: Android 4.4 kitkat
Display: Display: 5.7-inch display with 1280×720 Pixel resolution
Soc: Qualcomm Snapdragon 400 MSM8226
CPU: Quad core A7
GPU: Adreno 305
Network: 4G LTE
Connectivity: WI-Fi, Bluetooth, AGPS, and etc.
Main Camera: 8MP
Front Camera: 1.3MP
Internal Storage: 8GB
External Storage: Up to 32GB
Dimensions (Length x Width):152.1 mm x 79.2 mm
Battery: 3200 mAh battery(Li-Ion)
Recent rumors and leaks suggest that one LG-D631’s variant bearing model number LG-VS880 will be released as “G vista”, So AT & T might release the D631 as “G Vista” too.