I just rebuilt the entire rearend due to seal going out and losing all rear diff fluid. We put it all back together and now I hear an intermittent grinding noise while accelerating. I cant tell where it is coming from. Maybe rear of transmission or maybe front wheels. Did I maybe mess up rear bearing and yoke in transmission? Transmission and engine were rebuilt about 40000 miles ago.
Did you adjust bearing preload, pinion depth, backlash, and tooth contact pattern? All of those must be set correctly to avoid wear and noise. There is a tool you might be able to borrow or rent from an auto parts store that borrows them called the "Chassis Ear". It is a set of six microphones, a switch box, and headphones. You clip the microphones to suspect points, then drive around while listening with the headphones. You can move the microphones around to zero in on the source of the noise. Be aware that many mechanics have never seen or even heard of this tool. Suspension and alignment mechanics use it to find rattles, squeaks, and other noises.