Thanks! Now on to the second part of my post, have any of you other cub cadet owners had this problem of wheel slip, no traction? Without using weight packs and such.
Yes when I had a Lt1042 Cub, similar tractor, with a Variable speed pulley instead of hydro, and a different smaller engine, than yours, it did slip and spin slightly more than the John Deere La135SE that replaced it. But it wasnt a great deal. I dont know if it is because of the different tires or overall balance of the tractor. Please consider this, Lets say you do get that wheel spinning under control when climbing that steep hill. There exists the possibility that if the rear wheels are now firmly planted on the ground that the front end can come up and you go over backwards. Adding some weight on the front, down low, can help prevent that. Also try not to hit any rocks going up, as that can throw your front end up and cause this exact very thing to happen. I have BTDT and did not like it much. when the tractor came up and pinned my right foot on the "go" pedal and turned over all in less than a second. I managed to kick and shove it off of me. Right now because your wheels spin, you are not getting enough traction to "loft" the front end. Think of a "funny car" , take a light to begin with front end, throw in a high horsepower engine, and some really "sticky" tires, what happens? the pinion gear climbs the ring gear the axle does not spin because of the sticky tires and the front end comes up and the car starts to flip over on its top, the only thing that prevents it is the wheelie bars on the back.
Now if you are thinking of going down this apparently steep hill, you can loose control 2 ways, one is that sometimes small hydro trannys dont have a lot of holdback brakeing action so if you let off of the pedal, the tractor may still go down pretty fast because the hydro cannot hold it back.. This is usually pretty controllable and not too bad. The second way is if the hydro holds just fine, and you let off of the pedal, the tires stop rotating because the pedal centers, and brakes. Then the tires lose all traction with the surface, and you REALLY go down fast. This is really bad, you have lost all control of the tractor, and can set it sideways and overturn.
The point of all this "maybe coulda shoulda" stuff is to make you stop and think, it is possible that this hill is just too steep to safely mow with this particular tractor? Maybe just break out the weed whacker?
Not trying to scare, you, just presenting a few things, and they are worth what you paid for them

In the end it is still your tractor, your hill, your body and your choice. Could you post picture of this hill from several directions?
James K0UA