Same here. There is a clear difference for sure; Chevs of the 40s had some nice US-made fabricated pieces made from OEM thickness steel - I bought many panels for other OT but still 40s/50s GM products from them and was happy with their suppliers in every case. I may be confusing vehicles here but for sure the splash panel on my 49 3600 was from them. Now, it still needed fitting it wasn't a direct fit, but I was happy with it.
I bought fabricated running boards from eBay (long box, so impossible to find) but they were fabricated in the USA from nice thick steel and those actually fit without any massaging of the running boards.
I've had other panels for different vehicles that required even cutting and welding to make fit, just garbage. But if there are multiple contours, well sometimes that's still faster than me on my shadetree English wheel and bead roller.
