I have lots of GGD cars and they are my favorite passenger cars. I like them so much I am close to 70 GGD cars in my collection with several more on pre-order. Nicest cars for the price in 2 and 3 rail.
I don't want to disparage K-Line's cars as they were done a long time ago and at the time represented the state of the art for 3 rail scale length affordable passenger cars. I only have about 35 of their scale length cars.