im looking to trade my lifted truck described in my sig for a dually and i found one its a 96 ram 3500 cummis 12v with monster mack turbo, marine injectors, dual crome stacks, 4 weel drive, 5 speed manual transmission the guy says it runs great but needs body work. cant tell how many miles. has alot of peterbuilt mods on it though thats for sure. what kind of fuel economy could i be looking at? and does anybody have any main problems with these 12v? ive only ever ran 24v cummins. any opinions help thanks ya'll