Re: Is this a SSL-1? (Pics)
I'd say yes, looking at the way its soldered, and the lack of wrapping of the start and end of the copper wire through the eyelets, they're just inserted and soldered with a healthy dollop of solder.
Usually the older SD single coils have a sticker with the model number ink-stamped or printed on it - 1 for SSL1, 2B for SSL2, 3R for SSL3 etc. (new ones have a smaller sticker with the full model name and a barcode). Though it does look like it has a faded sharpie mark on the A string pole, looks like an M, designating it as a middle pu. Resistance should should be 6-6.5k.
With this one, it looks like the B string mag has been pushed up to minimize the impact of vintage stagger, trying to make the B sound more balanced with the rest (on a normal SSL1, the B pole is lower than the pu cover). I'd be careful, because doing that can break the wire inside, killing the pu. But, if the pu still has a reading, it should be fine.