Highway gear options/advice?

[Kell]

250 inline 6 with standard 3 OTT. My truck cruises comfortably at 55, anything above that is pushing it in terms of long term reliability I'm afraid. I would like to be able to drive on the highway instead of fearing it, I drive my truck a lot and this would allow me to drive it a whole lot more. I came up with 3 basic options?

1. I have 235/75/15 on there now, I would like to switch to taller tires anyway, but not sure if that will be a noticeable change? Any advice, or pics of taller tires (mine just look too small).

2. Switch the rear end out with an automatic? I've heard the rears are geared a little higher in an auto, this should bump it up some, but possibly make 1rst a little high?

3. Switch the transmission out, this is a pain, and finding a 3 speed with OD would be next to impossible around here. 4 speed floor shift loses some of the old school vibe I like about the truck, but I guess is an option. Have heard certain V6 S10 transmissions will hold up?

Any thoughts? Thanks

[benbloom]

i think ultimately your going to be happiest with an OD trans, with that said changing the rear can make a world of difference on the highway and if you go with something high like a 3.08 you wont need overdrive at all. of course your sacrificing some low end power there, so its all a tradeoff.

[barry1982]

Hi There,

If I was doing it, think I would try find a Diff from a 67-72 that had a 350/Auto. Pretty sure those had a little higher gear ratio than your 250/3 speed. In the late 70's early eighties GM offered a 3 speed standard with overdrive. I believe it was called an "A833" . They are rare..... (I have a couple). Both of mine came in 1982 GMC 1/2 tons with the 6.2 liter Diesel. These transmissions can be bolted to a Chevy V-8 or 6 cyl. They came factory with a "Hurst" type floor shifter.

[Mike C]

One nice thing about the 6 cylinder is that the 4.3 V6 T5 is a great transmission to swap in and they aren't real expensive compared to the harder to find more expensive V8 transmission. That would be my first choice for better all-around drive ability.

The other choice is to your point, taller tires. Or switching to lower numeric gears (you should have 3.73 so 3.07 would lower rpm 20%) but these also all reduce the low speed gear reproduction.

More difficult is the T5 swap, but more value to be had as well IMO.