The block in the old unit was old and grey, while the new one was very shiny... both of them very heavy. I kind of assumed that the new block might be a little better, or at least it was new and shiny. But I'm on G&L's site, and they sell an upgrade block, made of cold rolled steel, and it looks exactly like the one I had decided not to use. I don't know why I decided not to use it since the guitar sounded great as it is, why I thought I'd get an upgrade, but there you have it.
What is up with these blocks? Here they are:

Thanks!