I will tell you from experience that I had a k5with more weight than yours and had the th350 with 205, 37" tires and 4.88, it was revving up too high to keep up with 68-70 mph traffic and the result was overheating.I know there’s calculators for this but some actual user info is always good to consider too. Overall my K5 is a lightweight compared to a lot here. No winch, small tube bumpers, 10 bolt front, aluminum v8, th400 and np205. I’m going to be running 37s and except for BB will carry two spare tires. When finished with coils it will hit the scale loaded.
Will 4:88s be better than 4:56? Right now it has 3:73 and gets 18mpg and cruises at 75 no issue. It is a mixed use truck and will run around the state but not nationwide type runs. Eventually a magnum will solve this but until then what does the collective recommend?
I think he’s supposed to go to a 8l90 eventuallyI will tell you from experience that I had a k5with more weight than yours and had the th350 with 205, 37" tires and 4.88, it was revving up too high to keep up with 68-70 mph traffic and the result was overheating.
I put a 700r4 and all was good.
If you don't plan on changing your th400, and you want mixed use, go 4.56. It will be better than your 3.73 by far.
If you think you might change to an overdrive at any point, go 4.88
I think he’s supposed to go to a 8l90 eventually
If you will go with the 8l90 eventually it has a lower 1st and double overdrive so 4.56 would still be good.This is the plan but it's probably a year or so down the road. Maybe 456 would be best?