X-heads vs J-heads: what's the difference??

All the X heads came with 2.02 valves. Only some of the J heads did. Other than that, they are pretty much identical. Also, not worth a ton. I would say probably about 100 for J heads with 1.88 valves and maybe 200-250 for the X heads, maybe a hundred more if they are ready to bolt on and go. People think they are worth their weight in gold. They ain't.