bass - with a 4 speed you get more slow speed pulling power [lower 1st gear], doesn't do anything for top speed, any standard trans has a 1:1 top gear - an overdrive would get it to about 0.7:1 if you can work that out .... not sure you'll find a 3.55 gearset to fit your rear, so you'd need to find a complete rear that could be made to fit the truck that has a better highway ratio .... of course the 216 isn't the strongest engine so you don't want to be pushing it
if you haven't found it yet, the
old manual site might helpBill
