Seems like most questions here regarding out of level that I remember were the result of uneven tire pressure.
I believe front tire pressure differences should not cause the tractor frame to go out of level if the tractor is sitting on a flat surface, which I assume it is, if you are using a level to check to see if the frame is level. The reason this would be true is because the front axle has a center pivot. Raising or lowering one side of the axle, should change the height of the front of the frame, but not cause it to twist.
If you view the tractor frame like a rectangular piece of wood with three nails in it, one in the center of the front [representing the axle pivot point], and two at the corners in the back [representing the rear wheels] it is apparent that if you shorten one of the rear nails [ie, lower the tire pressure] then the front of that piece of wood will twist, with the opposite corner going up, and the other corner dropping.
But you have equal rear tire pressures. Did you measure the distance on both sides in the rear, from the axle center to the floor surface as I think someone recommended above? You should. Maybe the tires are not the same diameter for some reason.
If both axle ends are the same height from the floor, and the floor itself is flat and not twisted...then what could cause the front of the tractor to be out of level? If the frame were not bent, but somehow not bolted on square to the rear axle assembly perhaps? Not sure if this is possible.
Worst case the answer seems like it could be a bent frame...as was also suggested above...
The loader not hitting the floor even [or the snowblower] appears to me to be a symptom of the problem and not the cause. Whatever you would do to make these things sit level on the floor or when slightly above it, would not fix the root problem. Unless perhaps the loader frame were somehow twisting the tractor frame...which is probably unlikely.
Hope you resolve the problem without too much trouble.
I forgot, but did you say exactly what the 3/4 to an inch of lean actually meant. Over the lenght of a 2 foot level that is a LOT!