Can't remember how many jump seats there are in a DC9-51..........
If it's anything like the series 30, only one. And a tight squeeze at that, and once the seat is down and folded and the leg rests in place, ain't nobody going to get through to that cockpit from the SLF cabin.
Never flown the -9 but have ridden the jumpseat on occasion.
In spite of the cozy accomodations pilots always seemed to love the old girl.
Beech