Back in the '60s they actually put straight axles under cars to get the front up. This was done for weight transfer, rather than stiffness. You'll see this mostly on Gasser class drag cars, but some street rods were done that way too, although that was more for the look than performance. By the way, take a good look at the '55 sedan from American Grafitti and Two Lane Blacktop (same car), it has a straight axle as it was originally built as a Gas coupe drag car.

Bill Burmeister