At 05:16 PM 5/3/2015 -0700, you wrote:
I often wonder why more don't, too costly?Delrin/Celcon/"slippery engineering plastic" (invented by a slippery engineer?) is durable to the point of being nearly indestructible. It's also pretty much unpaintable and ungluable, and I suspect that unless you're Kadee and go to the painstaking effort to get the delrin to color match your paint as well as they do, most manufacturers just use styrene.
Most of the Branchline, IM, Red Caboose kits I've built have the stirrups in styrene and sometimes they are cold filled and fall apart. I've taken to just installing metal stirrups from the get go, if I have them on hand that are the correct style. Same for the grabs. The bracket grabs on BL's box cars are frequently a problem. Kadee makes some really nice ones in delrin, but the mounting points are different and you'll need to plug and drill new holes to use them... and then deal with trying to make paint stick to them.
For things like train line, gladhands, brake rods - any more I don't even try to cut the styrene parts off the sprue. Fortunately those are easily replicated with brass rod.