1998 Mazda Truck klonking sound

Hi folks.
I got a b4000 model, 4x4, when I go off road. In rocky terrain. I hear an additional klonk sound coming from somewhere below my cab, towards the bed of my truck. Could it be my tranny mount is out or is there something else that could contribute to this sound and yes I can also feel the sound.

I looked at my tranny mount but could not see any visible signs of a crack. But if a part was missing I would not know because it looks okay.I looked at the rear flange, shook it around, it seems normal play. My gas pedal does not get stuck so I don't think its an engine mount.
Would you know the problem so I can fix it.