New to me stake bed truck

[rumplecat]

Mine is a 3/4 ton with a 8 foot bed, I don't know how low it is geared but if I run it over 45 miles an hour my fuel use drops to about 4 miles a gallon???

 

[2002ford]

I don't have a drive shaft unfortunately. My truck is 410 open rear end???? Not even a gov bomb. I drive around 65 to 70 mph. It's my most useful truck except towing.