You guys ROCK !!! 

I think "Ken S." and "Pacific Northern" hit it right on !!!

I what I have concluded - The Black underframed cars are POST-War and the Greenish underframed cars are Pre-War.  Both sets (pre and post) have some 4 wheel and 6 wheel trucked cars (depends on the car).   My Combine with Porthole has black underframe and 6 wheeled trucks.  The 3 other coach cars have black undies and only 4 wheels. 

Bottom Line : I have to find PULLMAN, DINER and OBSERVATION car on Ebay OR just buy the PRE-War set and live with the differences........

I actually started with an SP Daylight Coach that I got from the first trip to the closing train store.  They only had that one and I couldn't find any on-line at all.   2nd trip to the train store I  found a ton of the PRRs.  I could have bought 20 cars BUT they only had 4 distinct road numbers. 

I guess I will just sell the SP  DL.  These are VERY NICE cars either way.   Also need to get me a K4 to pull them !!!

Thanks to you all for your input and help..........Joe

It looks like I have one (combine) with 6 wheels and the rest with 4 wheels.  Other than that - I can't see any physical differences.  I just did not want to have different types running on the same train like Standard vs Streamline - if that makes sense.   

The only way I can get the OBservation car is to buy the 4 set.   It is Pre-War.   I also need to get a Steam Engine which comes in Pre and Post war (3 road numbers each).

BTW - does the heavyweight have to do with the original prototype or the models ?  I can't tell any difference between the two types (4 vs 6 wheel).

I don't have a clue.  None of the boxes have that in the description.  The new passenger cars - 4 set - Bachmann #89300 have a description that includes "Pre-War".  Also, several Steam Engines of type K4 4-6-2 for PRR have either Pre-war OR Post War.  Assuming WWII.

I purchased four Spectrum Passenger Cars from a shop that is closing.  I got PRR 89011 (Combine), 89012 (Coach), 89013 (Coach), and 89015 (Coach).   

I need to know if these versions are Pre-War OR Post-War.  I am looking to buy the 4 car set #98300 which is Pre-War and want to make sure they match what I already have. 

I called Bachmann Customer Service and they can only look at descriptions (no help there).

Does anyone know my answer ?   

Also, what is the difference between the Pre and Post War versions of the Passenger cars ?

Thanks