Since you're doing a flush, I'm not sure how much fluid you'll use. When I drained mined, I put back in 8 quarts of dexron 6. Let me add that I spilled about a gallon of dexron 6 on the ground and had to go pick up 4 more quarts locally at $7/qt.
I don't think you can use the HD shafts unless you had the HD differential.
You should be able to get control arms through gmpartsdirect.com