Here are the differences with the Lift Lever (Upper Casting). The 129 would have this on the rear end of the frame. Pay attention to the welded collars on the frame.
Starting in the mid Q/L series, this collar disappeared and just a hole was in the same spot.
The original lift system used a "shaft" that went through the collars and the Lift Lever. The Second Generation, did away with the shaft and went to the Stud Bolt design (aka: Frankenstein bolts). See image below.
The Lift Lever remained the same, but it depended what your frame setup was that determined whether you need a "shaft" or the "stud bolts"
The shaft, I believe is NLA from Cub Cadet but it is simply 1/2" in Diameter and the length would be just enough tp span the frame width.