I asked HISUN Tech Support exactly that, and the answer is no.
I also found out that it is probably not my rear differential that has gone bad. It is more likely that the splines in the coupler have sheared. It's engineered for them to fail first, in order to save the differential.
In any event, the HISUN Tech Team is going to work with our local repair facility, to walk them through diagnosing and repairing our Sector 750 EPS. Hopefully it is just a $20 coupler.