I have a '67 Pro too. And yours looks to be in pretty good condition, JDT.

I've often wondered what makes some of them crack on the surface like that. I guess the leather just gets to a certain point and goes over the edge. I wish I could find that thing written by Tony Colegrave on "re-hydrating" old saddles. But I think he soaks his too, like Shipwreck mentions. For a couple of days, maybe. Allowing the water to fully penetrate each cell of the leather, which takes some time. And then shaping and sealing in the moisture with oiled waxes, etc.