Locking it up when you are sliding downhill is not only scary, it's downright dangerous. As your rig is front heavy it will have a tendency to want to swing out, think pendulum. A vehicle sliding sideways downhill can soon be one rolling down the hill. And I don't mean rolling tires either; I mean roof wheels roof wheels type of rolling.
Your instinct is to mash the brakes but what you should do is hit reverse ASAP, and keep your foot off the clutch and brakes, let the engine be your brake and drive downhill in reverse. A controlled descent in reverse is way better than an uncontrolled slide.
Glad it all worked out though, looks like the ruts held you in alignment down the hill.