Front at minimum. Any spring shop will have 'em, maybe dealers or parts stores too, or you can make your own. Rear depends on what your using the car for.
The clamps are very important for reducing lateral movement within the pack (side to side) and on the front half help make it act more like a link.
The concept behind the SS springs for drag racing is when the axle housing rotates, the front segment of the spring pushes up on the chassis (along with the pinion snubber). This maximizes weight on the slick. Even more so as the front end rises with the back. The more downforce on the slick, the higher traction. Anyway they get more freedom of the spring for lifting by removing the rear clamps.
The initial pinion angle and shackle angle are important when doing this. They're always important, but more so.
Original SS springs are not equal left and right. Different arches, different spring ratio (the amount of spring rate in the front segment vs the rear) and different number of leaves. You may have someone's home made project. ???
I would get some measurements off of the frame before concluding its the springs. Fender sheetmetal and driver's perception who is following you are subject to too many variables. measure from the subframes and on the axle, measure to the backing plate or something like that.
1973 Service Bulletin with diagram illustrating a misperception of dog tracking.
http://www.hamtramck-historical.com/images/TSBs/1973/02-04-73C page1.jpg
http://www.hamtramck-historical.com/images/TSBs/1973/02-04-73C page2.jpg
