I recently purchased a 1972 gmc with a 350 in it. The truck is in great shape and runs fairly well. The truck has a four barrel holley racing carb in it and I would like to replace it with a stock two barrel carb. Do I need to replace the intake manifolds and does anyone know of a good two barrel that would give me better fuel economy on the low end. The truck is a short bed auto with 4wd and I am getting killed in gas. Through 5 tanks of gas I am averaging less than eight miles to the gallon The truck is used to cruise and I rarely drive the truck more than 40 miles per hour. Any ideas would be appreciated. Thanks in advance for your responses.