Small Block ID help needed

I found a 74 Dodge Club cab truck in a salvage yard. It is a military issue truck, so it doesn't have the normal emissions stickers under the hood. I can't read the casting number or even see it because of the starter and manifold/exhaust. The one sticker that is on the fender says it is either a 318 4-bbl or 360 4-bbl (the emissions hose routing sticker). It is a 2wd and has a 727 tranny in it.

Are there any other obvious indicators that would point to which engine it is? It has a cast crank balancer with a fairly large counterweight on it and the casting markings I could see are a large 3 to the rear of the block and a large 6 towards the front of the block - these are both near the water jackets. The casting number for the year is x-x-74 (74 is all I could read).

Any help would be great!