A Quick Favor for an Old Friend is a main story mission in Red Dead Redemption 2 given by Uncle, as part of Epilogue - Part 2.
It's the 105° mission in chronological order of the RDR2 story mode, played with protagonist John Marston.
A Quick Favor for an Old Friend - Mission Details:
With his debts mounting and a barn to buy, John accompanies Sadie to hunt down the wanted criminal, Ramón Cortez, and bring him to justice.
Mission Objectives
Gold Medal Objectives (100%)
The following are the Mission Objectives required to obtain the Gold Medal in the mission "A Quick Favor for an Old Friend":
- Force Cortez’s men to flee from Rhodes within 30 seconds
- Get 5 headshots while covering Sadie with a long scoped rifle
- Get 4 hip fire kills
- Complete the mission without taking any health items
Note: You must complete all Gold Medal requirements in one single playthrough of the mission.
A Quick Favor for an Old Friend: Mission Info
- Mission Number 105
- Story Chapter Epilogue - Part 2
- Mission Giver
Uncle - Mission Type Mandatory Mission
- Protagonist (Playable)
John Marston - Location Beecher's Hope (Great Plains, West Elizabeth)
- Featuring
Ramón Cortez 
Sadie Adler