ARC has lots of oem parts that are not billet. http://www.arcracing.com/servlet/the-Stock-OEM-Engine-Parts/s/81/CategoriesAll the parts i have seen from ARC have all been billet parts
As already said, not it's not legal. At our track however it is legal as a local option we the racers voted it in. The billet rod is heavier and offers no performance advantage aside from increased reliability in an otherwise legal clone. Less oil on the track and less holes in engines has been a win for everyone, yet you don't HAVE to have the billet rod. Several of our front runners just run the oem rods.
X-2 Our local track in this area let's you run the billet rod from ARC as long as it is stock length, but alot of the guys still run a stock clone rod because it weighs less than the ARC billet rod.
But this is in the Pro Clone Class.
Why? They are a machine shop, not a foundry.
....Less oil on the track and less holes in engines has been a win for everyone, yet you don't HAVE to have the billet rod.