I did some looking at the numbers Kevin posted and it appears the 10A17650 was a different switch. The 10A23451 is some type of shaft. I speculate the change to the later 10A23729 switch also required a change to the transmission shifting shaft that reacted with the switch.
If you have the old switch in your hand I recommend determining who made the switch for Moline based on any numbers or manufacturer marks on the old switch. Search on-line and you might get lucky and find it. I would think the switch is some type of generic plunger style switch but I have never had one off before and I'm certain none of those systems work on any of the tractors I have in our collection. I bet most farmers disabled them back in the day. I think some of the last tractors made had a clutch pedal switch instead of this integrated "S" position switch. You may want to look into that as an alternative to the trans case switch that is no longer available. I bet you could fab up such a switch and bracket setup pretty easily and just wire it into the start circuit.