Zunnie, Welcome,
What is the story here?
Besides the subframe there is also hydraulic plumbing that is different that would need to be upgraded. I also believe the FEL frame brackets are different as the subframe mounts to it in front. You will also have to change the step stay kit. Also the entire seat assy and rops due to the seat connecting to it when in backhoe position. If you are buying a kubota BH specifically, which is the only one the subframe will fit, you will have much more into it than you will spend on a trade in. If you got a killer deal on or AKA free kubota BH than pricing this out may be a viable option. Also the AG tires will not clear the subframe. That is why R-4 tires are the traction option for the BX-24. Please let us have a bit more info on this and I'm sure we will get it sorted out.