Welcome to the forum, please take a minute to review the For Sale section rules, you need to have a location in the title. I fixed this one for you. Thanks JW
No problem. I'm not sure this seller is serious about the post because he hasn't logged in since he started this thread over a week ago. However, since you seemed interested in the Glock 30-variants:
The 30 has the "normal thickness" 45-cal Glock slide (like the 21). The Gen-3 frame is larger than the Gen-4 frame, and the texturing is different, too. Same double-stack mags.
The 30SF has the same size slide as the 30 (either Gen), but the 30SF has the smaller frame (supposedly equivalent in size to the Gen-4, but personally, I find the Gen-4 to feel slightly smaller). The 30SF frame has the same texturing as the Gen-3 frame, though. The frame should be marked with an "SF" on the right side upper-rear, in the "Made in Austria" area.
The 36 is a single-stack 45ACP, with a noticeably thinner frame and a thinner slide, too. The 36 doesn't accept the double-stack mags. The thinner slide is equivalent width to the 9mm Glocks.
Which brings us to the 30S. It has the SF frame and effectively the slide of the 36. So, it accepts double-stack mags, has a smaller frame, and the slide is thinner. It is almost an exact footprint of the Glock-19. In fact, it will fit in many Glock-19 holsters. Before the 30S was official, people did Franken-Glock the slide off a 36 and put it on the SF frame of a 30SF. The 30S slide is slightly different, though. I don't remember what Glock did to tweak for the match-ups, but I've read that the Franken-Glock wasn't 100% reliable. From personal experience, I find the 30S to be Glock-reliable; zero issues. It shoots surprisingly "soft", too; not snappy at all.