What gears do I need?

[78C10BigTen]

My 78 has a th350, 10 bolt with 3.42's and 31x10.5x15's and its almost 3k rpm at 65-70. I REALLY wish i had a 700r4 or overdrive of some kind, even a 5 spd!!!

 

[Vbb199]

I've got a yukon Grizzly locker and 4.10's turning 35's. If you aren't hauling anything heavy or towing regularly with your truck, you should probably stick with 3.73's. 4.10's will turn 60-65, but it's wound up pretty well at that point. If you want to daily it on the freeway at 65-70, you definitely dont want 4.10's or higher unless you plan on adding an OD at some point. Since you are a half ton with a 12 bolt, I'd recommend just getting a yukon duragrip and matching 3.73's if you can afford it. It will have good manners on the road and will still help a lot with traction.

https://www.jegs.com/i/JEGS+Perform...RpbvD6ulNMbXq5Nr3yiDTWkaoiiLkbU8aAgEgEALw_wcB

I agree ^ 3.73s would be best with a th350 for him

 

[Vbb199]

I agree ^ 3.73s would be best with a th350 for him

I run 4.10's on a 31" tire, but that's only because I have a 700r4.

If my burb was a th350, it'd be 3.73, even with a 35" tire.

That 2.55 first gear just isn't as nice as that 700r4's 3.07

And the 4 speed auto being .7:1 in 4th is a little better with a 4.10


I say gear off what your transmission can do, not what tire size you're running like so many traditionally do (of course tire size matters, but transmission ratios matter even more for a happy long life)

3.73 ftw!

 

[gmbellew]

I am thinking 4.56 for my 700r4 with 33s when I regear behind my 350TBI. but the OD is what makes that possible.

 

[Turbo4whl]

I run 4.10's on a 31" tire, but that's only because I have a 700r4.

If my burb was a th350, it'd be 3.73, even with a 35" tire.

That 2.55 first gear just isn't as nice as that 700r4's 3.07

And the 4 speed auto being .7:1 in 4th is a little better with a 4.10


I say gear off what your transmission can do, not what tire size you're running like so many traditionally do (of course tire size matters, but transmission ratios matter even more for a happy long life)

3.73 ftw!

This is exactly why I put a 700R4 behind my 402 BB. in my lowrider. Wanted that lower first gear and OD gear. 4L80E wasn't invented yet. My 700R4's were built with the goodies that were available back in the day. So yeah I kept a spare in the garage. One of the failures was shearing the reaction carrier into two pieces. I ran 3.42:1 gear with smaller diameter wide tires.

"If you want to play, you need to pay, but boy what a ride!" - I've said this before.

 

[Vbb199]

One of the failures was shearing the reaction carrier into two pieces. I ran 3.42:1 gear with smaller diameter wide tires.

"If you want to play, you need to pay, but boy what a ride!" - I've said this before.

It's like when i tell people I'm running a 39.5" tire on my solid axle s10 with a 4.10 gear. I have a gmt400 manual np241c custom clocked and mated to a 4l60e, powered by a healthy 4.3 cmfi

They **** when they hear that combo and think it's a turd until they go for a ride and see it'll still spin those boggers offroad in hi range, and low range is so low, in manual 1st gear, I can get up to 5mph until the motor is on the verge of exploding. It crawls over rocks and trails