I just went through this very same situation.
I replaced the exhaust on my '70 Charger R/T this weekend, did some research before deciding on an ECS system.
The old system fit and functioned fine, but some of the bends were not visually correct and I wanted one that was spot on to the originals.

I ordered an aluminized system with the ECS mufflers date coded for my car. I was very impressed with their system. All the bends & details are exactly where they should be. Fit was awesome, no issues whatsoever.

I asked Gardner if I could just buy their clamps, I was told they do not sell just the clamps & I had to buy a complete system in order to get them. No thanks.
My clamps were already in excellent shape so I just cleaned them up and reused them.