The motherboard layout, flex cable routing, and grounding screws differ between the T311 and T310. Using a T310 guide on a T311 will likely tear the GSM antenna flex.
The SM-T311 was not IP-rated, but the service manual specifies a around the LCD and rear cover. Samsung Galaxy Tab 3 Sm T311 Service Manual Repair Guide
The most utilized section of the service manual for the average DIY repairer is the mechanical disassembly guide. The motherboard layout, flex cable routing, and grounding