This is the correct TM scheme for a boxcar.
The proposed tri-color TM scheme is prototypical for a caboose.It is an attractive scheme and works on a boxcar as well,even if not quite prototypical.
I plan to order one.
Stumbled across this thread just today. May have had grandchildren underfoot (a blessing, indeed!) in July. Anyway, TCA issued a K-Line boxcar (649117IC) in the livery pictured in Boomer's post for the 1996 Dallas convention. Twenty years later, same state, same railroad, different livery.