From what I could gather from the tech section, the cheapest way to give your car an LSD is by swapping in an axle from another model or make. In the states, what is the most common donor in the junk yards for a relatively light and narrow axle with an LSD? I'm seriously considering the Datsun 720 pickup 4x4 front axle. Anyone use that?

I would just weld my diff, but then I'd be understeering on the autocross track,or sliding around every corner. I guess not using the stock diff housing would also put me in a modified class. Too bad NISMO diffs are rare and expensive.