CAT D7G with Cummins NT855 Engine: How to Identify the Correct Rebuild Kit?

[Gryks Machines]

I recently purchased a CAT D7G dozer with a Cummins NT855 turbo engine that blows oil from the breather and produces white exhaust smoke. How can I identify the exact engine model and serial number to order the correct rebuild kit without disassembling the engine?