3.73 rear end

[Pontiacgtp123]

I have a 1970 c10 and I believe it has 3.08 gears. It's a factory 350 with a 350 turbo trans. I found a 373 rear end out of a 69 6 cylinder with column shift. Guy wants 100 bucks for it. Are any of these rear ends posi or limited slip? How would 373s do with my setup. I was planning on swapping to a 700r4 in the future

[meatwagon83]

373 is alright with a three speed, i have them and run a th400, you will find your truck will accelerate much better, they are great with an overdrive

[LONGHAIR]

With a 44 year old axle, anything could have happened by now. I would open it up to be sure. You would be money ahead to swap the gears in your own axle if you had to put any work into the new one.

[Pontiacgtp123]

Yeah that makes sense. He said it had no problems or made any noises. He just wanted some 308s for mileage. I figured regardless a 100 bucks it's not a bad price.

[65Gregg]

I'm real happy with the 3.73 in my 65, it came with a 4.10 which was a little busy even with a 700 O/D. With the 1st gear in the 700 it's real easy to light the tires but still cruise comfortably on the freeway. My rear tires are about 29-30 inches tall.

[custom97]

Don't mean to hack this thread, but without a tag how can I tell what gears I have?

[bbcmudtruck]

Like mentioned above, these trucks are old and anything could have been done to them in the past. The only real way to know what gears you have is to pull the cover and count the teeth on the pinion, then count the teeth on the ring gear and divide them. Or you could do it by spinning one tire and counting the revolutions. Heres a vid that popped up when I searched on youtube for ya.

DIY: Check the ratio of your ring & pinion -...

[Clyde65]

My experience has been the 3.08's are fine for a TH350/400 if you are wanting to drive it daily and on the highway.
If you want get up and go, the 3.73's would be better.

If you want mileage, throw a 7004r in there and use some 3.42's

[Pontiacgtp123]

Yeah mine is just gonna be a weekend toy. I got a mild built 355 going in it and I think 373s would be perfect for what im doing. I go to a local car cruise in every month during the summer and allot off people race.

[DarkHawk]

I used to have a 90 454 SS 3spd. Auto. W/3.73. On the interstate she was wound up pretty tight. Just installed a 700 in my 72 and ordered some 3:73. I wanted 3:42 but the truetrac in a truck 12 bolt is only available in 4 series carrier (3:73 and numerically higher). After checking the rpm/mph calculator it says at 150 mph I would be doin just under 5k rpm and cruise speed at 65 was only like 2200. Seems like the ideal ratio (for me anyway).