4:11 to 3:07 rear end

[Isaiah92260]

If I get a 3:07 rear end for my 250I6 w/ 3 speed... Do I need to change my drive shaft? Or can it stay the same length? Thanks.

[lumpy63]

If your truck is a c10 with a 12 bolt year end and you are just changing to another 12 bolt the driveshaft length is the same .Depending on the year of the donor axle the u joint could be different .

[Isaiah92260]

Originally Posted by lumpy63

If your truck is a c10 with a 12 bolt year end and you are just changing to another 12 bolt the driveshaft length is the same .Depending on the year of the donor axle the u joint could be different .

Okay good to know thank you... I found one that is off of a 72... I have a 63

[lumpy63]

should be ok u joint should be #1310 same for both trucks

[Isaiah92260]

Originally Posted by lumpy63

should be ok u joint should be #1310 same for both trucks

Sweet! Hopefully I can pick it up!

[2manyprojects]

I did this swap. The rear is a bolt in but annoyingly slow with the 250, just something to consider. There are other options to make it more fun to drive and keep the 250, like a overdrive trans. Having a driveshaft made is pretty cheap and T5's are too if you look around.

[Isaiah92260]

Originally Posted by 2manyprojects

I did this swap. The rear is a bolt in but annoyingly slow with the 250, just something to consider. There are other options to make it more fun to drive and keep the 250, like a overdrive trans. Having a driveshaft made is pretty cheap and T5's are too if you look around.

Thanks for adding, I've been trying to weigh my options. I'm tired of maxing out at 65 with a screaming trans at 2700rpms. Plus I like to drive my truck on 2 hour drives to visit family.

I've heard about the T5... I've been thinking about it, I havnt had any luck finding any s10 versions, mostly canaria that require the modifications, plus a couple dues wanted too much..

[2manyprojects]

Ive bought several S10 T5's for $100 on Craigslist and at the local pull your own junkyard. They are out there just keep looking. The 3:07 is driveable but just don't expect to accelerate quickly.

Also a 700r4 will bolt to it if you wanted to go automatic I did that swap too and loved it.

[vince1]

72 I believe will be 5 stud and the panhard bar setup is different but doable. It will also be 1 1/2" wider and IMO looks better.

[TJ's Chevy]

3.07 is a bit steep, but will work. Engine has enough torque. I'd personally do a 3.42.

[Isaiah92260]

Originally Posted by TJ's Chevy

3.07 is a bit steep, but will work. Engine has enough torque. I'd personally do a 3.42.

Is it possible to swamp out the gears I have in my differential to a 3.07 or to a 3.42? And if so, Someone like me with no experience can do it, or should I go to a professional?

Last question, ha.... What are the characteristics of the 3.42? How would that run like with a 250i6/3Speed.


Thanks

[TJ's Chevy]

Originally Posted by Isaiah92260

Is it possible to swamp out the gears I have in my differential to a 3.07 or to a 3.42? And if so, Someone like me with no experience can do it, or should I go to a professional?

Last question, ha.... What are the characteristics of the 3.42? How would that run like with a 250i6/3Speed.


Thanks

For a bone stock 250 3.42 would probably drop your RPM's to 2500 at 65. You say 2700 rpm at 65? That sounds more like a 3.73 ratio, and if you have that ratio I'd consider an OD trans Or taller tires. My 64 GMC has 4.11's and 2600 RPM is 55 with 31 inch tires.
I'd consider 31 inch tires for yours and see what happens. That should be 2 inches taller than what you have right now. Bout 10 miles an hour faster per inch taller tire.

[Isaiah92260]

Originally Posted by TJ's Chevy

For a bone stock 250 3.42 would probably drop your RPM's to 2500 at 65. You say 2700 rpm at 65? That sounds more like a 3.73 ratio, and if you have that ratio I'd consider an OD trans Or taller tires. My 64 GMC has 4.11's and 2600 RPM is 55 with 31 inch tires.
I'd consider 31 inch tires for yours and see what happens. That should be 2 inches taller than what you have right now. Bout 10 miles an hour faster per inch taller tire.

No you are about right, I was heading up the hill to work about an hour ago and I was hitting 2500 at about 60, not sure if it was because I was going up a hill tho... I was making a ruff estimate when I started the thread...I don't know that exact ratio on my differential, I have pretty small tired that the PO said were new. Shoot maybe 31" might get me up at 70 ish at 2500 rpms then, I gotta find some prices on them now!

[60chevyjim]

in nc everything is so far away and the speed limit is 65-70 MPH.
so I love having 3:08 rears in my trucks ,
my 97 S-10 has A 4.3 V6 5spd and 3:08 gears
and my 93 GMC that I put A old carbureted 454 with a th350 in has 3:08 gears .
I use both of them for towing too.
I would hate to have any other gears is either one of them .
my 65 C10 is going to have highway gears too.

[padresag]

Originally Posted by 60chevyjim

in nc everything is so far away and the speed limit is 65-70 MPH.
so I love having 3:08 rears in my trucks ,
my 97 S-10 has A 4.3 V6 5spd and 3:08 gears
and my 93 GMC that I put A old carbureted 454 with a th350 in has 3:08 gears .
I use both of them for towing too.
I would hate to have any other gears is either one of them .
my 65 C10 is going to have highway gears too.

well that s10 be lighter than his c10 and the engine is more than likely a little snappier. and that 454 with a 350 trans will work wonderful with the 3,08. think there might be apples - oranges on that one
ron

[verdell]

I'd consider the 3.42's also...

[vince1]

The gears will not swap over, something about series 2, 3 or 4 carriers and different crown gear thicknesses.

[O'larry]

I think series 3 is 3.08-3.73 series 4 is 3.90 and up if I remember right