American Motors: Engine Identification, amc 360, stock engine

Question
I have a 1976 CJ5 with a V-8 engine and 2bbl carb.  I suspect it is not the stock engine.  The distributor is in the front so it is not a chevy transpant.  Told it was a AMC 360 by seller but he wasn't sure.  How do I tell what this is?  THe vin mumber is J6M83AA102138

Answer
Aaron,
According to the VIN, you have a 258 6 cylinder engine. Hmmm
If you have an AMC V-8, you can find its displacement cast into each side of the engine block behind the motor mounts.
The only V-8 engine available from the factory in your Jeep was a 304, though any late model (after 1966) AMC V-8 could be installed.
Kevin