The 89' TOFC cars were basically obsolete as soon as 48' trailers became common. There's no way to put more than one on a flatcar, although, in theory, a 40' and a 48' would fit. But how common were 40' trailers by then?
There were some modifications of drawbarring 89' flats into permanent pairs (TTEX marks) that could carry 3x 53' trailers.
http://canadianfreightcargallery.ca/cgi-bin/search.pl?display=short&marks=TTEXBut spine cars certainly became more popular.
