Thanks for all the feedback and photos.
From what I can tell, my P7 is a very early model (1979-1980), since it has a 4 digit serial number and no date stamp. It's a Lower Saxony pistol.
For those of you who own one of these early 80s P7's, here's something to note: the welds that mate the breech block to the frame have a tendency to develop tiny hairline cracks. Mine indeed has tiny cracks, and they can be very hard to find. I've come to learn that these cracks are usually nothing to worry about. My father is a mechanical engineer and a tool and die maker for 40 years now, and he explained to me that after the welds cool, the material contracts. Due to the contraction, surface cracks will form. But these are typically 'harmless' because they are only on the surface, and the weld underneath is strong. Check your P7's with a bright light and magnifying glass, and you might find these tiny cracks in the welds. Don't be alarmed if you do see them, your pistol is probably just fine.
I have a Don Hume pancake leather holster coming, and in the meantime, the P7 fits PERFECTLY in a Desantis pocket holster N3, which fits the Ruger SP101. Yes, the P7 fits well in a front pocket of jeans. This is what makes this gun so versatile: it is a full-sized service weapon that can be carried on the hip, OR, it carries like a pocket pistol if that is preferred.