I don't know if this is a new product or I'm late to the party, but Kadee makes #819 coupler boxes. They'll seat the 800 series and 740 series O scale couplers. The bonus is they're metal. They come four pairs to a pack. I've had three failures with Weaver shock-control boxes which are plastic (one hit and they're gone). The hole pattern is a bit different, but is looks like you could put in another longitudinal mounting hole if necessary. My Weaver 57-foot reefers are all going to be retrofitted.
