@geepboy posted:3) It seems to me that my best bet to identify post-war sized product is to simply ask on these forums as I have no experience telling the product sizes apart. Is that correct?
Post-war sizes were all over the place. Most post war diesels were 1/48 scale renditions, except for the obvious Alco FA's - these were O27-sized. Steamers and rolling stock for the most part were either traditional-sized (approx. 1/55 scale) or O27-sized (approx. 1/64 scale).
There are exceptions to the above, of course. One notable, the 4-4-0 General locomotive is actually larger than 1/48 scale, although not sure what scale it really is, or least based upon.
It's a rather steep learning curve trying to figure out what's what when it comes to the scale. Even modern day production Lionel trains haven't changed - they are still all over the place in scale sizes. So yeah, either ask, or start doing a lot of googling and searching. 
