Called "Rear pods" or "Rear skirts" over here in Australia (or "Rear Spats" in the UK), they were an option on the JDM supras (which also included the JDM side skirts). The closest you can find now are the veilside rear skirts, but they are a bit pointier
Here are the JDM ones:
And here are the veilside ones:
Here are the JDM ones:

And here are the veilside ones:

