I had the model number wrong 917.257561 (I had an extra 5)
The transaxle is a Dana 4360-82 with 5 speeds
I talked to Sears today and they want close to $500 for a new transaxle (part number 142608 or 161458) and stated that the $215 transaxle is not the correct one.
I have been looking at eBay and some of those seem to be options. I have a 5 speed, but if a six speed would bolt in I would just not use speed 6. I use the tractor just for snow blowing so I do not need the higher speeds.
I only paid $500 for the tractor, 42 inch blower and a homemade cab so I do not want to spend too much fixing it.
If you know the DIRECT bolt-up replacement unit part number (spicer, foote, etc.) please let me know. The eBay seller wildcat just told me that a spicer 6 speed would work, but I am wnat to be sure.