I just made a deal for this 1997 SG-1. I just gotta go pick it up.

I already own two of these and I've been looking for a third one for a couple of years.

On the left is my 1998, and the one on the right is a 2000
I'll be doing the same mods to this one as with the other two. Added neck pickup and 3-way toggle. I already have a set of Seth Lovers to go in this one.
Why on earth do I need 3 of them? I dunno, they're just fantastic guitars. I love the size and shape of the neck. I like the lack of a pick guard, and I prefer the control layout to the standard 4 knob scheme on other SGs. These also have 24 frets.
According to the SG Wiki, the SG-1 was introduced in 1995 and then in 1998 was re-named the SG-X and at that point Gibson introduced the Summer Beach Series in bright colors and added a pickguard. This one is a 1997, and the seller is the original owner. Included with the guitar is a pickguard that is the same style as the ones on the later SG-X models. It appears that the SG-1s all came with the pickguard, and they left it up to the customer whether they installed it or not. You will notice in the picture above that the one on the right has SG-X on the truss rod cover. That's because it is from 2000, so it's definitely an SG-X. But, still no pick guard! I can only assume that Gibson continued the practice of including, but not installing the pick guard at least on the ones in the standard colors. The other two I own did not come with the pick guard, so I'm guessing they were lost by one of the previous owners. An interesting note; both of my previous ones were bought right before Christmas.
Here's a pic of the 1997 with the pickguard (not installed, just sitting there).

So there you have it. More than you ever wanted to know about the Gibson SG-1/SG-X.