Thumpping noise, when down shifting

I just purchaced a 1996 Toyota Rav 4. The car is clean in and out, well taken care of.

I feel a problem has apeared. When driving along, and coming to a stop light, I push in the clutch to down shift into neutral, and I feel, and hear a thumpping noise in the rear.

I’m not sure what this could be. I would be happy for any advice out there.

Thank You Randy.