I can't really say for sure but most subframes start at or about the rear loader mounts, and pass back under the rear axle. they usually attach to the lower front three point arm pivot points or the axle itself. they then extend back to where your current mounts attach to the backhoe. The upper three point toplink that came with the backhoe acts as an upper stabilizer, tying it all together, The subframe is there to help support the weight of the rear of the tractor and prevent torsional twisting at key frame points of the tractor such as the engine/bellhousing and the transmission/rear axle. Contrary to what I said In my earlier post. kubota has sold a lot of their backhoes without a subframe and swears by them. Make sure you keep all mounting points tight with no slop in them. And close the 3pt lifting resistance valve while operating. This will prevent bleed down thus helping to keep it all tight. That is the little knob facing foreward under the front of the seat.