OIC, bed RAIL caps. The width should still be the same. The length would deffinetly need to be changed. Even a short box is longer then a blazer bed. Other then triming them to fit, I don't see why it wouldn't work.
On a simular subject. I've thought about getting a tonneau cover designed for a short box, cutting the fabric to length, and running that on my K5 in the summer. Sort of a cheap half cab.