i have been logging the mileage and fuel costs for the burban i have, 82 with a 6.2, unknown mileage, odo says 24493...who knows exactly. i bought it with 22642 miles on the clock, has 24493 on it now, i put a total of 75.5 gallons of fuel in it, at a cost of173.50
:draw
. by my calculations, thats 24.5 miles per gallon!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!, and after the b&m shift kit set up for r/v towing, it runs great, shifts good and has a considerable amount of power than when i bought it. now just to deal with all the rust 
:draw 
i have found out more info...it has 240k on the odo now...kinda figured it wasnt in the 100k department, but by contacting the previous owner..found out they put alot of $$ in it before unloading it..