Kubota frame mounted backhoes

Been looking to buy a used BT900 or BT1000 backhoe for my L35 tractor.
My tractor is already set up for the BT900 and has the factory frame kit installed. The problem I am running into is that Kubota hasn't made them since about 2005 so having a bit of a hard time finding one which is why I was hoping someone could tell me if possibly another model BH might fit and work. Basically what I am asking is do all of Kubota frame mounted backhoes use the same 4 point attachment. They look the same BUT the spacing for the mounts may be different? Has anyone ever mounted a different model BH on an L35 with any success?

Yes I have called several in state Kubota dealers. They all just want to sell me a new tractor. I've been researching this issue quite a bit and have learned that the BT900 and the BT1100 both are a direct fit for the L35 but the BT1000 and the BH90 are not. The sub-frame would have to be modified. The question is how much will it need to be modified? I found a place that will sell me a brand new BH90 for $4999 which is a great deal (I think). Has anyone ever modified the L35 sub-frame to use with a different model backhoe?