**** Thanks Steve. You're right but I have ignored the treatment of the flat-bottom top major rib because EVERYONE in the hobby biz has ignored it (in HO scale) with one Accurail exception (I think; from memory). ****
Your memory is pretty good - Accurail does make a rthin/3/3 end for some of it's reefer kits. Bill Welch posted a teaser shot a year or so ago ahead of one of his clinics. The pic did include a rthin/3/4 end. I queried him off list and he turned me on to the Accurail ends. I've got four sets here that I'm attempting to convert into a viable master suitable for casting enough in resin to cover my needs (Four dozen or so for GN, SP&S, and perhaps other cars). Unfortunately, my skills at removing ladders, brake housings, and tack boards from curve services is lacking . . . . . . ☹
**** There are dozens and dozens of examples where that feature is missing from our models. :-( ****
Yep Almost 20K cars with the IDN-2 end. I'm doing some Excel work to see if I can't do a nice job of summarizing Ed's data by various IDN-2 configurations - maybe a nice summary might temp someone to consider marketing additional end options.