I want to know what the question really is, and the answer.
There is no "final drive" on a Cub Cadet. Not by a tractor standard anyway. If you wanted to be technical, the final drive would be the last reduction before the wheel. But there is one before that "final" reduction.
So, did you originally want to know the total reduction ratio between the hydro and the wheel? Or did you just want to know what the last reduction is?
Is the answer the "engineers" gave the ratio of the R/P? Or the total ratio between the hydro and the tire?
So, I made a quick trip to the parts book. I looked up the trans for an XT3. It shows all the gears, and the tooth count of all of them, minus the pinion gear on the hydro. (Says not available.) But I know the trans in the XT3 is the same as the trans in a 3235, so I looked it up. Low and behold, all part numbers are the same, but that diagram actually lists the gear on the hydro and gives the tooth count. So, in less than 10 min, I now know what the ratio of the hydro to the ring gear is, and the ratio of the ring gear to the "final drive"..... AND.... what the 27.7:1 ratio is that was stated by CCC! And I didn't have to make a phone call, or wait 6 days to get an answer.
Math and reading are so cool.