The Kato website says they're 70 ton! They were made for their 1958 cu ft covered hopper. Glad to hear they're 50 ton !!!
The N&W Kadee model is #44324. I have documents for 2 cars in that series.
N&W 44456 44000-44999 XM furniture 1/4/59
N&W 44672 44000-44999 XM lumber 7/17/59