"gripper pattern" u bolt question

If I found a set that didn't have the proper knurl, I'd look REALLY close to make sure they're not Chinese Trash. In a street car, I don't know that the knurl missing is a deal-breaker, but I would never run them without the flat. That flat is what keeps them from crimping your axle. Even if you use the proper torque spec, you're still concentrating that load on a MUCH smaller area.

Call your local truck/axle shop. They might have what you need just laying around.