Boat anchor???

I've read that some folks with a 3406c and 4:11 rears want to use their trucks for boat anchors.... I wouldn't think of it without finding out if something can be done for better performance. Different rears? For some reason mine goes up hill in what ever gear I choose with out slowing down? Could it be in the turbo or driving style? No of fence intended but it does seem odd as they say they are having trouble.... Oh and mine is a 1977 359 no emissions....