I think you are referring to a rain gutter extension spout. The gutters themself are just a piece of angle or something similar that would not be damaged by a tree limb hitting them. The ADD-ON PLASTIC SPOUT EXTENDER like shown here just snaps in place...

I see these listed in various places like even WALMART... These four units are available from CAMCO part number CAM42134... Just search GOOGLE for RV PLASTIC SPOUT EXTENDERS...

Bet you can get these CAMCO items from AMAZON... Just looked $14.47 for pack of 4EA... You may want to check on one that is still in place and see if you can find a CAMCO part number of your exact part model. Probably different sizes available...
Roy Ken