Here are pictures of Williams box car from 80's NASA set. Started life in the AMT/Kusan era. 10-1/4 by 3-1/4. K-Line Timkin 10-1/2 by 3-1/4. Retooled from the NASA car mold. Lionel post war Rutland 10-1/2 by 3-1/4.
Williams brass PRR box 11-1/2 by 3-1/2. MTH Premier Katy box 11-1/2 by 3-7/8. All care measured coupler to coupler.