Engine revved like I was in neutral?

I was driving for about 30 minutes and just pulled away from a stop sign. The truck did not make any weird noises but seemed to be shifting into the next gear when the engine revved like I was in neutral. Tried every gear even in 4 wd and had nothing. Had towed home on flatbed, not cheap. The seem to lock in park but in any drive or reverse the wheels roll freely. Is this a catastrophic failure of the trans? No unusual noises were heard at time of problem.