swathdiver
Full Access Member
I hear ya but there's a huge difference with 4.88s in a 4L60 and a 6L80.I used to have a '76 K5 blazer w/373 gears, TH350 and 35" tires and it was an absolute dog. Zero acceleration, took forever to get moving (had a 350 engine). I installed 4.56 gears in the rear (removed the front drive shaft prior to) as I wanted to see what sort of difference it would make before doing the front diff. It made a subtle difference, acceleration improved but not dramatically. I then installed 4.88s and it made a much more notable difference, woke that little 350 up and it made for a much more enjoyable driving experience, especially on the trails. I then put 4.88s in the front diff. I sold that thing as fuel mileage wasn't measured in miles per gallon, it was measured in gallons per mile and was a rust bucket. But the gears made a big difference.
As long as the vehicle is in the 'green' with the selected gear ratio per those gear ratio charts, it will be fine but for 35s in a 5-6k lb vehicle, I'd go 4.56 at minimum.
In this example the stock NHT with 3.73 gears smokes the 4-speed truck with 4.88s ratio wise.
My 2012 came with 3.73 gears and has been running 35s for over ten years. About 2 years ago we had to do a reman transmission at about 130K. Right now the tires make the final drive ratios equivalent to 3.42s which we have in our other 6-speed trucks. 4.10s would bring the 2012 back to 3.73 rpms. Would you still counsel steeper gears?