SV DADIDOC

This came on right after an oil change at my GMC dealership ( but no connection). As I let up on the gas pedal I can hear a very light " knock or click" sound as if something is disengaging when de-accelerating, where I release torque completely. Then, when I start to apply the gas, and torque is lightly reapplied, I then get this LOUD knocking sound until it shifts into gear. If I apply the gas fast, I will pass through and get into gear and not hear the sound. Again, when I lightly apply gas and torque, it will make this sound . I am looking for a sure thing diagnosis from a technician who can recognize this nd tell me what needs to be replaced. Terrified that it " could be" this , or that, or this other thing and my bill grows quickly ! I have heard the ticking sound from flex plate, understand a shudder from a failing torque converter, but this one puzzles me. Here is a youtube clip with the noise.

This came on right after an oil change at my GMC dealership ( but no connection). As I let up on the gas pedal I can hear a light " knock or click" sound as if something is disengaging when de-accelerating, where I release torque completely. Then, when I apply the gas, and torque is lightly reapplied, I then get this LOUD knocking sound until it shifts into gear. If I apply the gas fast, I will pass through and get into gear and not hear the sound. Again, when I lightly apply gas and torque, it will make this sound . I am looking for a sure thing diagnosis from a technician who can recognize this nd tell me what needs to be replaced. Terrified that it " could be" this , or that, or this other thing and my bill grows quickly ! I have heard the ticking sound from flex plate, understand a shudder from a failing torque converter, but this one puzzles me. Here is a youtube clip with the noise.