A big battle ensured with the other railroads having clearance problems with the cars and PRR embargoing the other railroads from its lines if they wouldn't accept the cars in interchange, it wwas very shortlived and the new AAR standard became 10'6" for boxcars.
As some will know, this story is a great irony. In the 1920s, when several Western roads were building tall automobile cars, Pennsy led the objections of eastern roads to these "oversize" cars. Of course "tall" at that time merely meant taller than an X25.
