choosing correct gear ratio

[zoelhebert]

i have a 94 gmc sierra 2 wd i tow a trailler that weighs about 6000 lbs i only have 3:08 gears would 3:42 gear be ok id like to be able to cruise around 60 to 65 mph right now at 55 mph its got his full load.

[DmaxMaverick]

Welcome aboard!

3.42's would be an improvement. If you are now able to just hold 60-65 with your load, dropping the GR from 3.08 to 3.42 should do it well.

You could instead consider an over/under drive (GearVender, etc.), which would essentially do the same, while retaining your current ratio for unloaded driving, and/or an additional overdrive. I'm seeing more of them pass through Ebay and Craig's List at reasonable prices.

[zoelhebert]

sorry if i dont now but whats a over under drive and where does it goes does it mouth to the end of the tranny .

[DmaxMaverick]

Also known as an "auxiliary transmission". Installed behind your OEM tranny, and either automatically or manually controlled.

[JohnC]

Are you sure it's 3.08? Didn't even know that was available!

I had a '93 HD standard with 3.42 gears and 6K# was about the limit. An auto would do a little better, an "S" code engine a little worse. Unless it's an "F" code and an auto, I'd go with 3.73 gears.