Just bought a 6BT to fit to my 4wd motorhome here in Oz.
Used Cummins engines are pretty expensive here too, parts are also hard to come by.
My engine was a genset engine and it is a Cummins full rebuild in 2009, has the later style block etc but full mechanical injection so it is a bit of a mystery as to what bits fit when converting it to vehicle use.
Currently chasing a few small parts to enable me to fit it in the vehicle, most from older 1st gen engines.