We have a smart azz saying at the shop. When customers ask if they can bring their own parts? We say do they go to a resturant and bring the Bacon and Eggs?
It just never seems to work out?
We speck out the parts that we install....period!
Structural corrosion could be inspected by a body shop. We have a bore scope, and a seer snake that we can inspect inside rails. Also look for metal fatigue, cracks, spot welds popped etc.
I hope this helps. Go upgrade and have fun!