Personally I would say no because chinchillas are very sensitive to molds and old wood is a bad idea. Molds produce chemical compounds that are very toxic and live molds can be inhaled and cause pneumonia which is usually fatal. If you have fresh wood from your yard it is still advised to bake it to sterilize it before you put it in the cage. Old wood that has been hollowed out and has been on the ground will have those mycotoxins in it that do not always break down if baked. It would be cool if you could though or I'd have lots of stuff like that in my chinchila's cage.
