I recall one of our Baja trips this happened to someone's D2... while they didn't have the spare part, someone had a DI tensioner (or a different-year/engine D2 tensioner, can't recall) and they hobbled the parts together to make it work. I was impressed at the level of ingenuity displayed; some of that may have had to do with how dark it was getting; no one likes driving in Baja at night so everyone worked quickly. The belt didn't sit correctly on the tensioner (about 15% of it was sitting off the pulley due to the part not being designed for it), but hey, it was enough to get through the trip. Hearing that another one bit the dust, this certainly seems like a key part to keep in the spares bin for a Disco.