Gear Ratio Selection

[vicnation]

My '76 K10 has the original 350/350 and NP203. I plan to upgrade the drivetrain but I need advice on what gear ratio to use. The current gear ratio is 3.07 with a Dana 44 and a 12 bolt. I will be installing a 383 pushing about 420 lb ft torque mated to a 4l80e and an NP205. I will be running 33" tires as well.

I would like the truck to have good launch from a stop and be able to cruise easily at 70 mph. What gear ratio is recommended?

Thanks...

 

[yevgenievich]

Probably 4.10 would be better match with 33" tires and a 4l80e. Can check online gear calculator for your comfartable cruising rpm

 

[gpmorgan]

I recently installed a set of 410s in my son's tahoe with 35s. It was a great improvement.

 

[Honky Kong jr]

What they said....4.10s.

 

[4WDKC]

My truck had 342s and 33s with 700r4 when I bought it, It would have to drop out of over drive to speed up on the interstate and when there was any type of incline, I swapped to 410s and 315/70r17s and the truck is much better. I bought the wheels and tires used so when they need replaced i will be going back to the 33" height.

 

[vicnation]

Thank you for your input. Really appreciate it.