Buying a new garden tractor advise needed on model

I own a small 3/4 acre but the yard in hilly. About 10 degrees or more on front and back and between 15 and 20 on side. I am looking for a strong transmission (better than a K46) with locking diff for use because I'm always slightly pulling a hill or going down one or riding sideways on one. I have researched and researched until I think I have found a suitable tractor. What do you think of the Husqvarna GT48XLSi model? I am torn about the motor but I have seen a reviewer that says it has a K66 transmission (I would like to make sure about that) which I think makes me happy. I have to stay with the size of the 48 due to my building doors which are 56" wide. I might be able to do a 52 but it would be tight and looking at the 52 they don't have the lock diff. Any thoughts on this mower or suggestions on another? I will have to have it dealer serviced so it needs to be a good dependable mower. I am a widow doing my own mowing and want a stable, easy to use dependable mower.

Thanks