There is no replacement for displacement. The 318 isn't a bad motor either but these trucks need torque to get them moving. They aren't light A bodies that's for sure!
1997 Dodge Ram Sport 4x4, 5.9L Engine
KRC 2.02 Street Ported R/T Heads, KRC 210x Cam, Comp Cams 1.7 Rockers, F&B 52mm Billet TB, M1 Intake, K&N FIPK II, Accel 21 lbs/hr Injectors, MP Headers with True Duals, MSD 6AL Ignition, MSD Blaster HVC Coil, Magnacor R-100 Wires, ASP Crank Pulley, APS 2800 Stall Converter, APS Valve Body, SCT X2 Hemifever Tuned PCM, 180° Thermostat