I had went through a process where we had located a rear, set up the pinion angle and welded the perches in a 69 dart. I can verify that the driveline IS not centered to the vehicle. I seem to recall the driveline is off set to the right. However, it looks like in the OPs pic the engine is sitting to the left at the rear of the drivers side valve cover. I would think the manifold is hitting something if the pic holds true. Also, i would think you would notice at the trans mount etc. it may be an optical illusion.