The scheduled production date is from 1972. ( The 1973 model year ran from August 1st 1972 - July 31, 1973)
C56 is bucket seats (for 1973)
XW in the interior code is white and black.
J - Dodge Challenger
H - Price class -High
23 - two door hard top
G - 318 CID
3 - Last digit of model year, 1973
B - Assembly plant, Hamtramck, MI
238137 - The 138137th VIN assigned at this plant for the 1973 model year.
000 is upper door frame paint - none.
31297? is the Vehicle Order Number (VON)
U is build to specifications for US sale.
EN2 - End of sales codes, assembly line two.
I have a fender tag decoding service, if you want it all typed up on a nice letter. You can find the ordering info here;
http://www.hamtramck-historical.com/services-d.shtmlT/Ake care,
Barry