Rebuilding the 12 Bolt - What Gears do you Recommend?

[C10agent]

Hey guys,
I am going to be rebuilding the 12 bolt in a couple months and I had a buddy recommend I go with 4:10 gears. I am running a 350 with vortec heads and 700r4 tranny and the 12 bolt is a single fire whiner. I want some scratch coming off the line, just don't want peg out on the highway going 70. Any thought and what are you guys running?

[leddzepp]

We need to know what size tires you are running. Generally with that engine/trans combo 3.73's are a good choice.

[C10agent]

I am running the Wheel Vintiques 17" Rally Wheels with 245/50/17 Generals all the way around.

[THE BOSS]

when I bought my 72 it had 4:88 for the dunes
I took them out and put in 3:73
if I had to do it again I would go even taller gears, low 3:00 and I have 36" tall tires. the engine runs kinda high RPM's on the highway.

now with your having a lock up converter, you might be alight with that choice. but if your going to drive on any trips, I'd go taller than 3:73

[Already Gone]

If you not going to run a mega horsepower motor and just use your truck as a cruiser with the occasional highway trip, I suggest 3:42"s will give good power and decent fuel economy.

[MARKDTN]

I'll second the 3.42 as a good all-around gear

[C10agent]

I was thinking 3.73, but this truck is literally just going to be a cruiser and not a weekend racer. Thanks for the advice!

[Ridgeclimber]

I have a LQ9 6 litre with a 4l60e trani. I installed a eaton posi carrier into mine. I kept the 3.73 gears just to keep the cost down. Works good. But if I was going to to it again I would of used the 3.42 gears, just because these trani's have such a low first gear.

[67ChevyRedneck]

Originally Posted by C10agent

I was thinking 3.73, but this truck is literally just going to be a cruiser and not a weekend racer. Thanks for the advice!

Good choice. I've been running a 350/700R/3.73 combo since 2002. Great overall set up. Don't get super excited about high MPG. Expect 12-13 around town and 16-17mpg on the highway (70-75mph is closer to 16, 55-60mph has gotten me close to 17 a few times but it's hard to go that slow!)

[67 chevelle]

unless you are runnin a very tall tire say 35s or 38s , I would not go with 411 gears with a 700r4 , they have a very tall first gear , that works well with 308 thru 373 gears

[C10agent]

I am really glad I got y'all's advice. The buddy that is rebuilding was really pushing for them. Good to know. Thanks!