Will the lug bolts from my 4-lug Fuchs work with Diamond Racing wheels, or do I need a different shape? (Flat, ball, taper?)

What's a "Diamond Racing wheel"? Knowing that might help us to help you. If you have an example, just look at it. If it's a ball seat, be sure it's the same diameter ball. If not, find a lug bolt that fits. Whatever you do, be sure the threaded portion protrudes through the back of the wheel AT LEAST a quarter inch beyond the thickness of the rear rotor and the hub. After that, the front will be no problem, as it doesn't have the added thickness of the rotor to contend with.

The Cap'n

Thanks Cap'n. That's the brand. I'll be picking up some "Pro Series" models soon. I may have to wait until I get mine so I can look them over first hand.

In the mean time I'm hoping Joe or Josh or some of the other guys who run them might share what they used.

I just looked at 'em. Looks like you're gonna need the lug bolts for steel wheels, which are much shorter than the lug bolts for Fuchs wheels. Reading the fine print is difficult for me, but it talks about a taper on the bolt hole. Whether or not this taper works with a ball seat bolt, I can't tell you.

The Cap'n