Denny Anspach wrote

That except for the short shank #153 semi scale couplers, the other
Kadee semi scale couplers (58, 78) are on prototypically excessively-
long shanks... Personally, I see no visual advantage at all to using
semi scale couplers of any variety unless the shanks are short...

Denny,

Consider that most (uncushioned) model draft gear do not extend further
than the end sills, and then the extra shank length (.031) plus the smaller
coupler head means that the car-to-car distance is closer to prototype
than you might expect if you're only considering the shank length. So if
you insist on using only the "short" shank #153 then you must also mount
your draft gear so the distance over pulling faces of the couplers is
set according to the prototype.

Tim O'Connor