hello vickraft, i've got a 99 silverado with the 4.3v6 and the 5 speed overdrive tranny. in fourth gear at about 2000 rpm, i'm going about 65 mph. and it has power to climb hills or pass and go faster if i need it . but, 5th gear is useless below 70plus mph. i don't use it unless there is a straight stretch and no officers in sight. the rearend is a 3.23 ratio, and i wish now that it was a 3.73. hope this helps.
