Anyway, the approach I took was to screw the lid of the original coupler box to the car, then snap the other half onto it. The mounting screw has to be carefully countersunk to clear the coupler parts.
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David, what size screw did you use for this application? And do you have a good source for them? This is a nice approach for cars with a good solid mounting surface.
I was trying a few schemes on a covered hopper last night, where the only available surface is the thin exposed center-sill, so I'm looking for
very short screws that won't be too obtrusive. One possibility is
this set screw, which is 0-80 x 1/16". If I first glued the pocket top to the sill, I could tap continuous threads through the top and sill, then put the screw in far enough to clear the coupler w/o countersinking. This would provide lateral strength. A short flat-head screw would also work, but I haven't found any shorter than 1/8", and I don't really want to cut them if I don't have to.
Thanks,
Gary