For Seneca owners, max torque is somewhere around 62 mph. I generally run slightly above that - 65 mph and 1800 rpm in 6th gear. At max torque we get the best performance out of the Cummins in terms of longevity and mileage. Don't know where the sweet spot is for the Ford V10.
Freightliner custom chassis division offers classes for class A owners on the engine, trans, and chassis where they explain a lot of that stuff. Wish Freightliner offered that for the M2 chassis RV owners.
2015 Jayco Seneca 36 FK
2016 Jeep Wrangler Unlimited tow
2010 Tiffin RED 36 QSA - gone
2011 Monaco Monarch class A - gone