Right rear turn signal and reverse lights do not work?

Okay, it sounds like it's probably a bad connection, possibly the ground. Testing wise you will want to pull the lamp out and get to the wiring for the lights. Remove the bulbs. Now turn on the 4 ways and use the test light to probe the socket, the pin fed by the dark green wire should have pulsing power. Now turn on the marker lights and check the pin with the brown wire. That should be on. If those both work the next step will be to connect the test light to power and test the black wire that is the ground. The ground connection is shared by the reverse light as well as the brake and marker lamps so it is the logical issue to look at first but we need to rule out the power side first. The other item with the ground being gone is that those lights would come on and try to ground through the other lamps, that increases the load and blows the fuse.
Attached are the diagrams for both lamps. The ground in question attaches to the rear frame rail and have rusted out before. A very quick test to verify the ground being the issue would be to simply run a jumper wire from the black wire in the harness behind the light to a good ground and see if the lights return. If they do I would probably add a new ground for both sides, Both are black wires that go to the frame.