I am in the process of fixing the brakes on my gmc 7500 dump truck. What I have found is that everything but the brake drums are available. It has 15x7 wedge brakes on it, the number on the brake drum is 2658 gunite, which I looked up on the internet and it says it is an obsolete part. I was wondering if I could put a size smaller brake shoes on and use a different 15" drum that is made for the shoes? has anyone ever had this problem before?