Frédéric, one thing you have to consider is replacing the plastic wheel sets with metal. Running plastic wheels on HOT summer track will melt the wheels. I've seen it happen.
Mike, thank you for the feedback! It just seemed a bit strange to me, that most flatcars show up to eight stake pockets on each side. Were those meant for heavier loads, or longer cars?
Frank, thanks for the attentive advice, however those are blackened steel wheelsets. I've had my own share of worn-down plastic wheelsets and I like the low center of gravity those wheelsets lend to the waggon. So, no worries there