Boyd, I have some observations from experience. There are the "tabs" on the car body itself and then there are two plastic "hinges" on the dump tray base. They are all subject to break, though the log dump cars (minus the dump bin on the car) seem far less prone to break than the coal dump cars. I've also had better luck with the early MPC cars than the more modern and recent ones.
That said, I've come up with a design where I cut a piece of basswood to fit on top and over the tabs on the car body itself. I've done this to both repair busted ones and to strengthen ones that are not broke. On cars I'm going to repaint, it's no biggie, but on cars I'm leaving as is, I sand smooth the basswood and then paint it to match the car color before I glue it into place. I've gotten the point where I now automatically make the improvement to all my dump cars.
The hinges on the tray piece are harder to fix, though I have tried successfully. At this point, I just keep a few extra tray pieces on hand since they are not all that expensive.
As far as looks, yeah, Lionel always seemed to have pretty sparce decoration on the dump cars. When I repaint them (I have repaints in Norfolk Southern MOW, Conrail, Conrail MOW, Lehigh Valley, Jersey Central, Penn Central and NYC) I add lots of extra decals which really is a nice finishing touch. I also put stripes or a bright warning color on the side of the car that the load dumps off.
I need to get a digital camera so I can takes some pictures of what I do for the fix. It's worked well for me and it is actually something Lionel could easily incorporate into the design of the car which would be a big improvement.
I've also taken some cars that had broken tabs on them, modified the cars, painted them yellow and put decals on them for TTUX cars - which is pretty effective. They make nice 027 TTUX trailer cars. The mods I make to the frame allow both the Lionel 027 shorty trailers or the longer 9 inch trailers to be placed on the cars.
This is an older pic, but illustrates how good the cars can actually be made to look when repainted. I've since discovered a decal source that makes some "warning" sorts of decals.
