You can buy just the inserts, you know with the 1/4" hex on one end and the clutch on the other.

I bought a few at the local hardware store.

you can also get the bits from McMaster Carr.
http://www.mcmaster.com/

page 2755 in the online catalog, all 5 sizes for less than $6 total.

part numbers for the short ones:
7188A31
7188A21
7188A23
7188A24
7188A32

longer ones available, look at the page mentioned above.

Should be fine in the impact, and if not then they were cheap...

Grigg

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
---All pictures---
"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-