Adding Derale Trans Cooler behind existing factory cooler?

[TheAutumnWind]

So leave it routed through the radiator and stock tow package cooler and finally out through the Derale cooler?

Some people bypass the radiator. In many vehicles (IIRC toyotas has this issue?) that have a tendency to have failures the coolant and trans fluid can get mixed up.

Not sure that that is prevalent with our vehicles, however if you live in a warm climate and overcooling is not an issue than you might choose to bypass the radiator completely.