I have a 1973 charger 340 magmun. I ran vin# WP29G3G sayes it's a 318. Was this special option,is their a stamp on block and where that says size. It has bubble hood with 340 magnum emblems.

 

The engine size will be on the driver's side of the block in raised numerals,behind or slightly above the starter. The hood was probably changed out at some point because the "G" in the WP23G3 is the code for the 318.