does anyone have any comments about the 3.38 rearend ring and pinion sold by the host?thinking about replacing the original rearend gears in my 58.the truck is all original and runs great with only 31,000 miles,but;the gas milage is pretty bad with the 283.also,as i understand, the 3.38 will raise the top speed from 65-70,and enable the truck to be driven on the interstate.