What is the difference in over and under shank couplers and how much difference in length is there between short, med, or long
go to the Kadee site they have a lot of info on couplers.
Lex
on a regular shank coupler, the shank is centered where it connects to the coupler head. overset couplers have the shank connected higher, and underset couplers have the shank lower. they are designed for situations where the coupler mount is not at the standard height, and compensate for the difference by raising or lowering the coupler head in relation to the mounting box.