Sorry Gary, but here are stats on loaded and unloaded milage
Equipment: 2001 International 9400i condo, 12.7L Detroit, 10 speed direct, 2.64 rears, 6x4, pulling a mildly ribbed dry van:
Bobtail (18,250 lb):
55mph: 12.5-14mpg
Empty (32,500 lb):
55mph 9.5-11mpg
65mph 8-9.5mpg
Fully Loaded...