Ok, that's weird, and makes zero sense. I'm glad I spent the extra and got the GroundForce kit for mine; it's marketed as a kit for the 4x4 QC trucks, and fit was great.
Here's my QCSB 4x4 with a GF 2/4 kit:
Before:
After:
Here's my QCSB 4x4 with a GF 2/4 kit:
Before:


After:

