I'm looking into buying an F150 with a 3.5 Ecoboost. It list a 3.15 ratio rearend. I have a 6000 lb trailer to pull. After comparing the different engines I noticed the 3.7L FFV and the 5.0L come with either a 3.55 or 3.73 rearend. Will the ecoboost with the 3.15 gear ratio be sufficient to pull the trailer or would it be better to have the 3.55 or 3.73?