I would look for one that has a subframe mount style rather than using the three-point lift arms.
The backhoe puts a tremendous amount of stress on whatever it is mounted to, way more and in different directions (sideways and up) than normal pulled 3pt implements do. Consider that the backhoe can lift the backend of the tractor off the ground and move it left or right a couple feet.
My NH backhoe subframe fell apart from metal fatigue at the point the backhoe attaches to the subframe. It is made from reinforced c-channel. I had it rebuilt at a welding fab shop. It has seen a lot of use though. Just digging dirt is not so bad for wear. When you start messing with rocks and stumps it really works the backhoe and what it is mounted to.
The repeated stresses, down, up, side to side, some amount of twisting too, is more than I would want on the lift arms. Lift arms are designed to lift and pull.
There have been some NH tractors broken in half at the bell housing-transmission by 3pt mounted backhoes.