There are several Center Partition Flat Cars
This is an accurate listing from all the observations I have made over the last 20 years.
Thrall Car 63'
Northern Pacific
Burlington Northern
Western Pacific
Union Pacific
Milwaukee Road
CNA
TTZX Trailer Train
Thrall Car 73' long
British Columbia Railway
TTZX Trailer Train
TTZX TTX
Gunderson 73' Long
MIDSOUTH
Andrew