Does they do it in reverse as well? And what is the timing of the two gears making the same noise. Both at the same
time or did one do it for a bit and then the next one a few months (weeks?) later. And finally did you do an oil change
before the noises started?
It could be something in the gear, but it also could be the damper plates. The noise is more like a clanging or hitting
of two metals together. These are the plates that connect your engines to the transmissions and they have either
springs or rubbers depending upon your set up.
The gear issues are more typically sort of a groaning thumping noise or a grinding of teeth noise.