I have Marlin duels 2.28x4.7 and its usually more than low enough,,  I have only ran a few obstacles where i would of liked a little lower,,,(tight large boulder sections, and extreme off camber climbs with anywhere from 15-20ft drop offs,, I used the clutch when needed) Being that i wanted to go lower  dunno why,,, I built a triple case setup ready for my Xtra cab  ,,, Running a R151F w/Marlins Total Spline 2.28 input, ending with 2.28x4.7XDx4.7XD on a Lefty T-Case with Marlins Chromoly 30spline F+R outputs...