JerryT,
I know nothing abou the Kelley BH but something about the JD48. The JD 48 goes on and off the tractor pretty easily. I assume the JD 47 is similar. The posts I have read about other backhoe seem to indicate some bolts have to be messed with to get the non JD backhoes off the tractor. On the JD48 you add/remove a couple of pins, connect/disconnect hydraulic hoses and use the rocker arms to get the backhoe mounted/unmounted. Pretty simple for the most part. Certainly easier than messing with bolts.
If you are going to consider a backhoe have the dealer show you how to mount/unmount the implement.
Later...
Dan