I own 3 sets; one is the original that I got via the TCA offer, and two are ones that I obtained later - because they were so cheap. Here's what I can tell you...
The original set has 2701 in its UPC code but other than that the set number is not displayed on the box. Paperwork has a 1991 date on it. As I recall, when I received it the cars they were too "pink" and they ran terribly (fortunately they loosened up after awhile). I opened up my original set - the colors were not as bad as I remembered them - I don't know if I got the replacement shells and swapped them, or if my perception of the color has changed. If I did swap shells, I don't recall whether or not they came with the details or if I had to take them from the originals.
Subsequently, I've obtained two more sets that appear to have better color - they were too cheap to resist. Both of the later sets have a sticker on the box saying that the item # is 2701-A. However, each set has a different pair of cars!
The shorter South Shore cars that were produced later (2000ish?) are much better in just about every respect.
IIRC, K-Line also sold identical cars marked for Reading. If you find a set of K-Line interurbans in a black box, they're probably the same as the South Shore set.
These are just generic interurbans - the ends, windows, and roofs are all wrong, so I wouldn't obsess over the details - perhaps make your own grab irons and see if you can find a set of pantographs that will fit.
I'm not usually a rivet counter, but I grew up near the South Shore, and I've always hoped that someone would make a semi-realistic set. Not holding my breath, though.