just wonder'in- many folks tell me how poor mileage I am going to get from my 305 V-6 61 GMC half ton. it is stock with the 4 speed floor shift trans. I have change gears in a ford 8.8" years ago. I am wondering if there is enough to be gained by trying to locate a good set of gears to swap out in the rear end- say down in low 3-1's? I am not planning on pulling it hard and expect the big engine can lug plenty good. not sure if slowing it down with gears so it would run more slow at highway speeds of say 65 to 70 max would be worth the cost. no doubt some after market sources out there that might supply them but interested in advice from experience.it won't be a primary driver and I'm kinda guessing I'd have to drive several thousand miles to regain the expense even though I can do the work myself.it currently has right around 4 to 1 likely 4,10? 2 WD 1000 series.