Time passages here too.
This may be a very good challenge, or just a very left-field aircraft!
I first thought we might be looking at the aft end of an on-wing turboprop installation of some kind? Or it could be a weird twin APU exhaust set-up... The unfaired trailing edge either side hints at the latter, but if this is a tail, where is the rudder? Or, it could be (and probably is) something very exotic.
The same starter for ten as last time from me...
Did this aircraft enter series producton?