The 4x4 Dodge trucks I had during that era didn't seem that high to me, so the big tires might be throwing it off.

One look at the front leaf springs where they bolt to the axle will tell you if the springs are stock, Dodge used a 3 leaf spring pack with the springs bolted directly to the front axle. more leafs, real thick leafs, or any spacer means a chassis lift kit.

One look at the front cab mounts will tell the story about a body lift. One 2" high rubber bushing between the frame and the body is standard. Body lift kits usually had 2 rubber bushings stacked, or an added spacer above the bushing. If the cab was lifted, its likely the bed was also lifted the same amount. Dodge either built the truck with the bed on a 3/8" rubber, or the bed was bolted directly to the frame (depending on the year). .