You can buy them at Camping World, probably other places. They come in a four pack. Be careful, there are two different types that look similar. One clips on an existing gutter. I put these on our last travel trailer that didn't come with spouts. Our Voltage's have a model that mounts behind the gutter, hold better, but are harder to replace. You have to remove the vinyl trim, there is likely a screw through the vinyl that is caulked over. Pull the vinyl back, and remove the first several screws holding the metal gutter on. Carefully cut the caulk, so you can pull the gutter out slightly. Be careful not to cut the roof membrane! Remove the broken spout. Insert the new one, there's probably a screw that goes through the gutter and through the spout. I used an awl to start a hole in the spout, once it was lined up. Replace the rest of the screws, apply a little caulk. Replace the vinyl trim, screw, caulk, and you're good to go.
I've had 3 of the 4 break on our 2013 Voltage. I think the get brittle in the sun, and crack.
If you need me to look up the brand & part number, let me know.
2013 V 3105
2016 F350 King Ranch CC 6.7 diesel dually