The Shimano XT M786 rear derailleur can be mounted on a traditional hanger or as a direct mount on compatible newer bikes. The direct mount reduces weight and flex plus creates a little more room for faster wheel changes on thru-axle bikes. Other features include a direct cable path and a stabilizer switch. When activated tension on the chain is increased which reduces chain slap and prevents chain drop.
The M981 features Shimano's Shadow design where the derailleur is tucked in under and behind the cassette where it is less likely to be damaged from the perils of off-road riding. The shifting performance is also improved due to the closer position to the cassette. The Shadow design places priority on a low profile with less body movement for increased performance and durability. When in high gear, the derailleur has a profile that is a full 15mm less than a traditional rear derailleur. That means it barely protrudes more than the quick release skewer nut.