They are the same. The K after the 7 denotes the version relative to that model. In this case, no differences.
FYI, the first version was called an HRX217(K0)HYA, then was an HRX217(K)1HYA, then the HRX217(K)2HYA, and finally the HRX217(K)3HYA. 0, 1 and 2 versions used an internal cone-clutch design, and the "3" changed to a slipping belt design. As I recall, the 0, 1 and 2 used an optional cost-up accessory side-discharge chute, while the 3 has an updated rear door that discharges clipping downward (no other parts required).
Thanks Robert.
I just bought the HRX2173HYA yesterday. I then saw online a model with a k in it, thought maybe there was a revision done that may be important.
