818 is a boxed set of 4 800-large series cars, 812, 814, 816 and 817. 819 is a boxed set of 4 600-series cars, 653, 654, 655 and 657. 650 series cars do not follow the same numbers as the early cars or the larger 800 series. Then there is also small 4 wheel 800 series. 2800 series and 2650 series cars were added when Lionel developed automatic couplers in 1938, and a few 3650 and 3800 series automatic cars came along in 1939.

Yes it is confusing, but when you have been into trains for near 50 years, it comes natural.

If you are to get serious about trains, I strongly recommend that you get the book Lionel Trains, Standard of the World, published by the TCA. It is the most complete and accurate book on all prewar Lionel, O, Standard, OO and accessories. It is not a price guide, but those are worthless these days anyway. You should be able to find on on Ebay. Make sure you get the second edition and that the paint color chip chart is included. This book will help you make sense out of Lionel's prewar numbering system, show or describe all variations, years items were produced, department store specials etc etc. Jim