Is there a transmission relay for the lock converter?

I have a 1994 850 wagon with an automatic transmission (not turbo) that just started to make a resonating noise when on the highway or when accelerating hard. At highway speeds I can hear a slight click near the shift level and then a resonating noise in the engine bay on the driver side. The noise only stops when there is another click near the shift lever due to a change in the car's speed. The noise is simliar to a loose piece of metal resonating.

I assume the click near the shifter is the torque converter relay signaling the coverter to lock, but the resonating sounds eminates from the fuse box area. I have check the heat shield and all is tight.

The car has 129,000 and has not yet had the fuild change. There is no noise when driving in the city or at low speeds and the transmission shifts very smoothly. The fuild does not appear or smell burnt.

I noticed that the mechanic did "tighten the transmission cover" the small 1X5X1 cover in the front of the transmission due to a small oil leak. What does this cover and would the thing under the cover buzz if over tighten?

Any help would be appreciated.