[OnePutt]

I just read JPsuffs post and the next one by Bulls. First thing is, all shafts will have what is referred to as a spine, not just steel shafts. And second, the spine is not the same as the weld where the sheet metal is welded together. The spine can be in an entirely different location on the shaft. And NO, steel shafts are not welded at each of the steps. The steps are just where the shaft changes to a different diameter. The only weld runs along the entire length of the shaft.
If anyone here has every done a spine test on a graphite shaft, they can tell you that all graphite shaft have a spine also. In some shafts, it's quite easy to locate it, and in some it's rather hard to find, or at least not as big of a spine in terms of how the shaft flexes.
While I totally agree with FPsuff, that shafts need to be aligned before being tested in a frequency meter, it's not as easy as just aligning the shaft by the weld. If that was the case, there would be no need to do a spine alignment on steel shafts. All you'd have to do is look inside the shaft and look for the weld, and align them my the weld. Unfortunately, it doesn't work that way.