i recently bought a box car no. 70038ct. i had seen a cpuple of pics of this series and was wondering what the "ct" was for?

I would think that the box car is a 40' double sheath car built under authority of the USRA. A government agency that oversaw the railroads during WW1. Cars were built to government specifications. Many of the cars were built on speculation and not paid for by the assigned railroads. The CT you mention was the initials of Columbia Trust. The holder of the title to the car until paid for. Columbia Trust was an agency of the US government. You don't mention the railroad name in your query was it Boston & Maine ? I didn't know the B&M had any Columbia Trust cars. Would you mind E-mailing me a photo of that car? Regards, Al