Gentlemen,
USUALLY, Mopar used Carter AFB or AVS carbs and most used three (3) step primary step up rods. It was easy to tell because the 3 step rods and step up pistons had a domed cover; the 2 step up piston assembly used a FLAT cover plate.
The 3 step metering rods (and corresponding pistons) provided a smoother transition for primary fuel metering from cruise to power air fuel ratio.
REMEMBER, when turning the fuel system the key is AREA PRESENTED in the jet/metering rod ratio. It must be calculated to get the effective AREA by measuring the diameter of the metering rod step diameter and converting this number to square inches. The jet diameter is known, so convert the jet otifice diameter to AREA in sauare inches and SUBTRACT the metering rod step area to get the accurate jet presented area. You cannot just subtract diameters as area varies as the square of the diameter. Fuel feeds are usually calculated in pounds/hr or air/fuel ratios from stochometric (14:1) to best power ratio (spprox 12:1) allowing for uniform distribution.
Carter carbs are easy to tune....it just takes a little common sense and time.