star wars iv R2D2 and lucas behind the scenes

This photo, behind the scenes during the making of Star Wars Episode IV (the best episode), shows George Lucas standing next to R2D2. I am not sure if it is RD-D2 or some other model. Maybe it is a R2-D2 prototype mock-up?

Cool Star Wars fun fact: Tauntaun is a cold -weather beast that resembles a fur covered lizard that walks on its back legs plus has curled horns. Belonging to the ice planet Hoth, these beasts are frequently found inside huge herds, rushing around the icy plains on their big, three-toed paws. They boast tough, coarse lips so as to let them to graze lichens plus moss off open rocks for food. This is not the only type of food they eat they sometimes eat small rat like creatures as well. At night they search for night-time shelter inside caves, because they are not able to stay alive in the tough night weather.

They had been used with the Alliance as a type of horse throughout their occupancy on Echo Base. The Tauntaun has a distinctive, arctic hardy blood that  makes it possible for it to stay alive on the Hoth landscape. There are a few varieties of Tauntaun on Hoth but they all possess the same distinctive blend of reptile and mammal qualities. The Tauntaun is the Wampa ice creatures preferential supply of food.