[drh4683]

Originally Posted by zeno

The model number starts with a single S. This makes
it a big store set. Probably came from a major retailer
although we could sometimes get them as drop ins.
K-line is the switch over to 1st gen System 3. Top
line 25" & 2 19" sets came that way. In L-line almost
all were 2nd gen S3 sets ( 9-160 ) with a few uprights on the
lowest end sets.

73 Zeno

Thanks for all the great photos, Tom! This helps a lot.

Zeno, what exactly did the "S" stand for and how did that make it a "big store" set? I also see some models that start with the letter "T" as well, typically sets from the early 70's. Were those sets for institutional use? What was a "drop in"? Otherwise, most models typically start with the familiar letter associated to any given model year. What made the "S" models different enough to justify to that designation?