The Northern was made in 1947 with SIT, the 0-8-0 was made in 1947 and 1948 with SIT. I have personally seen and examined a 1947 version of each. They were part of a 1947 4622 Complete Railroad set. Both of these two engines were DC. The set was owned by Dennis Bagby at the time and is documented in Greenberg's Sets, Volume III. A picture of the 1947 DC 322 with SIT is on page 34 of that book as well as the DC 342. Finding an AC SIT 332 or 342 is going to be possible but difficult. I think the concensus is none were made in 1946. Either of these engines, AC or DC, are hard to find.