Pretty close to buying my son an 86 Ramcharger. The guy who is selling it has no idea which engine it has and neither do I! (It's not the original). I'm pretty sure it's the 318 as there's a lot of room in the engine compartment. Is there a quick way to tell the difference between a 318 and a 360?

 

http://www.mymopar.com/enginecastnumb.htm

if that does not work research the VIN, auto zone or a wrecking yard with a cross reference manual might be able to help too.