sphc11

As of December 31, 1950, the following quantities of flat cars were rostered in North America, according to the Official Railway Equipment Register (ORER). These "Top 16" owners represented more than 75 percent of the total.

Railroad Flat Cars Models1
SP, T&NO 8,439  
MILW 5,296  
NP 4,779 Red Caboose (via InterMountain)
SOU 4,133  
C&NW 3,560  
PRR 3,381 Bowser
ACL 2,861  
SAL 2,789  
UP 2,726 Red Caboose (via InterMountain)
Walthers
GN 2,576 Red Caboose (via InterMountain)
ATSF 2,332 InterMountain
Red Caboose (via InterMountain)
NYC 1,901 Red Caboose (via InterMountain)
D&RGW 1,705 Red Caboose (via InterMountain)
RI 1,658 Walthers
L&N 1,653  
CB&Q 1,642  
1Does not reflect "Craftsman" level models, which are available for almost any road. 
Such models are offered by Funaro & Camerlengo, Westerfield Models, and Sunshine.