As Andy and others have pointed out the old #78 coupler has a special shank and centering system that's unique only to the #78 coupler. The inside of the #78 box has a wedge or chevron shaped centering post that matches the pivoting hole in the #78 coupler. No other coupler works on this post. Several smaller manufacturers have molded their coupler pockets for the #78 coupler with the chevron pivoting post.
Not long ago we changed the centering post inside the #78 box to the standard round post to accommodate our "whisker" couplers. The original #78 was difficult for the average modeler (if there is such) to assemble so we assemble the #78 here at our plant. To save a great deal of labor we looked into using our #158 scale head whisker coupler in the #78 box and when we knew the whisker couplers would work in the narrow box we went ahead with the change. The #78 has been discontinued as a retail product but has been replaced with the #178 using the #158 coupler in the modified #78 box.
However, all is not lost concerning the #78 coupler. The #78 is the coupler we are using in all of our freight cars so we are still producing the #78 coupler for our in house use and we'll continue to do so until we get around to changing over to the whisker couplers in our cars, an eventuality.
Upon special request we will sell the #78 coupler "only", no box, with centering springs for #2.35 per pair plus shipping, directly from Kadee. Also note that the coil "centering spring" for the #78 is the common #622 "knuckle spring" used in the #5 size of couplers.
Thanks Tony for your comments too.
Kadee Quality Products
Sent: Friday, May 11, 2012 11:19 AM
Subject: [STMFC] Re: Southern Car & Foundry tank car kit questions
Hum, the little bags that contain the photo etch fret and brass grab irons also has a pair of couplers in them.
Jon may need to deal with the changes at Kadee, especially with the two new tank car kits he is planning to release.
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