As Tinplate Art has stated, the newest edition of Standard & 2 7/8" Prewar Vol. I, was updated in 2015, covering 1915-1928, with over 1800 photos, and very well documented. The Vol. II will contain O gauge, from 1929-1942, and is due to be released some time in 2020. The price of either book is $100.00, but well worth the investment, if you need to know anything related to either series.
I met with Bruce Greenberg last October, in York, to have my collection of all the variations to Lionel's Torpedo locomotives, which was the 1588 wind up, the 1668E (2-6-2), & the 1688E (2-4-2) locos. As an example, the 1688E had a total of 18 different body castings, from 1936-1942, and used three (3) different motors, during it's production. I have all the variations, of the 1688, and know the different variations of the 1588 and 1668. I spent close to two years researching, all the variations, and was completely surprised with the results.