Hi Chris,
Many thanks for sharing the files! I think the difference in appearance is due to a complex self-induced appearance migration in Inventor. On Inventor 2013, Inventor adopted the new standard Autodesk Appearance and Material Library. The way the appearance was defined in Inventor was very different than the Autodesk Appearance Library. To avoid dramatic change in the look and feel of migrated parts, Inventor team migrated the old Inventor appearance to closest match in Autodesk Appearance Library. However, the migration wasn't done fully. Otherwise, the look can feel could be even more drastically different.
The look and feel of such migrated part still has inconsistency between Shaded mode and Realistic mode. If you turn on Realistic mode, you will notice the difference in D version, not in C version. I think the appearance of D was migrated to 2013, while the appearance of C was added in 2013 and later.
On 2017, the prior parts with migrated appearance are migrated fully to Autodesk Appearance library. You can open the D-Nose iPart.ipt and do Rebuild All. Then go back to the assembly -> Update. You will now see the appearance on both parts looks the same now.
Many thanks!
Johnson Shiue (johnson.shiue@autodesk.com)
Software Test Engineer