The pinto spindle is lighter and stronger than a metric spindle. It also will make the steering faster because it is shorter. One more thing most circle trac cars also use rear steer Nova/Camaro lower A arms so that it moves the ball joints foward 1". If you plan on running the Pinto spindles with metric lowers You must bend the tie rods for clearance or maybe some one sells them now but when I ran them the tie rods bent very easy from any contact. If You run the Nova lowers then the lower A arms bend. I don't Know what it takes to bend a spindle but it is a lot I have not bent one in 8 years a racing on dirt. I'm not sure about the Nova swap
