If you are uncomfortable with the life expectancy of your current shifter I would suggest you get the Allison part number, and then go to ebay and set up alerts for anything that might be interchangeable with the one you have.
The same is true of almost anything that you might need in the future but don’t want to pay full price, such as a reader for the engine, transmission and ABS.
http://http://www.ebay.com/itm/Allison-Transmission-Shift-Pad-29529429-29538371-29538372-29538373-90030926-/121206760696