In all most every case with a cummins HP equals MPG. My 95 started at 18 mpg stock. My 07 was 16 mpg hwy. Now low 20s.

67 Barracuda, 470" B, Glide, FuelTech FT600, Precision, Ptc, QA1, Calvert, Smith racecraft, Afco, Dana 60. 275 radials