Oh good! Another Aussie.
If you ask your question in the the Excavator section, you might get a really well informed reply.
All I can tell you is that anything is possible with buy-outs and take-overs in the machinery world. What I do know is that in Japan, manufacturers often sell their superseded technology to competitors so you may well see a newer Sumitomo that looks like an older Hitachi under the engine cover.
Sumitomo were first sold in Aus. as Sumitomo-Linkbelt when Kato were top of the tree in excavators, obviously using the tie up between the two companies and the well respected American name to give credability to an unknown Japanese name. Surprisingly, before long Sumitomo were using what was then a very advanced variable displacement pump group of German design.
In the early eighties, Mitsubishi and Komatsu had the most advanced circuits and were the first to use "logic elements".
Cat finally realised that they couldn't build an excavator to save their lives, so they bought the Mitsubishi designs and rights (I'm not sure about the factories) and Mitsubishi excavators were no longer sold, while Cat magically became very good!
