The NV149, NV246, NV261 and NV263 transfer case have a engineering design flaw in the oil pump/rear case interface.The oil pump overtime can wear a hole in the rear case causing fluid loss and total transfer case failure.  We are pleased to announce the new upgrade rear case design, it an OE performance unit, includes thicker wall design to prevent pump wear, includes output busing and out put shaft bearing.See the other transfer case parts that we can supply on our web site.