Lionel's Engine Product Numbers

180xx, 280xx and 380xx are generally the high end steam locos.

186xx, 286xx and 386xx are generally the starter set locos.

   Both Greenberg & TM Books publish excellent Price Guides for all Lionel trains (back to 1901), with catalog #s, dates of production & they usually include the cab #s (on the cab of an engine), which frequently is different from the catalog #. (Example: Back in '83, Lionel's cat. #8378 Wabash FM "Trainmaster" had cab #550; their first SP "Daylight" 4-8-4 had prototypical cab #4449 & was cataloged as #8307.)

   Lionel has used #s up into the "99000" range & TM's Price Guides list items by category: F-3 together, Hudsons together, etc. TM's web site is: www.TMBV.com.        

   Hope this'll help. DK 

for MPC, a good rule of thumb is the engine always started in 8 (for the most part), the next number would stand for the year it was built.  The other 2 just seem to be what ever was next in series.    There were times when Lionel would only put the prototype number on the engine & the catalog number would not appear.  

For example - the 8600 NYC Hudson, the 6 = blt/catalog date of 1976

The rolling stock gets a bit more complex, but off the top of my head - 

9200 - Boxcars, Tank Cars, Operating Boxcars, Large Hoppers, B/W Caboose

9800 - Standard O, Billboard Reefers

9700 - Boxcars, Large Stock Cars

9400 - Boxcars, Large Stock Cars

9600 - Hi Cube Boxcars, 

9300 - Gondolas, Crane Cars, Tank Cars, 

9100 - Flatcars, Cabooses

9500 - Passenger Cars

9000 - Small Hoppers, lower end SP caboose, small flatcars

6300 - Gondolas

6000 - Small hoppers

7000 - Some Mint Cars

I know  there are more, but that's all I can get out of my brain right now.