has anybody swaped rear ends (diff axle and all)

[oldblue1968chevy]

Im lookin for beter gas mileage in my truck....is there a whole axle assembly out of another vehicle possbily that would maybe have a higher gearing or something....jw maybe im just all screwed up...but curious to see if anybodys pulled a rear end outa another vehicle or truck that'll bolt up to a 68 lwb fleetside.....lookin for gas mileage here thanks

[drewdude92]

i would like to know this also ....bump

[nightmare]

i don't think that this is possible with coil spring trucks. IIRC there were no other vehicles that had that type of setup. If you have leaf springs, you may have more choices, like from a newer chevy/gmc pickup. But even then you may have to move the perches that the axles sit on.

you may want to look at getting a numerically lower gear ratio to boost mpg. but i think that the lowest you can go is 3.08's.

[LuckyHenriksen]

Can't you just find a rear end out of the same year of truck but with 3:08 gearing?

[nightmare]

Originally Posted by LuckyHenriksen

Can't you just find a rear end out of the same year of truck but with 3:08 gearing?

yes, that is possible, but my understanding of the initial question was to find an axle out of a totally different vehicle. my mistake if i misunderstood.

[Bus Ted Knuckle]

Originally Posted by nightmare

i don't think that this is possible with coil spring trucks. IIRC there were no other vehicles that had that type of setup. If you have leaf springs, you may have more choices, like from a newer chevy/gmc pickup. But even then you may have to move the perches that the axles sit on.

you may want to look at getting a numerically lower gear ratio to boost mpg. but i think that the lowest you can go is 3.08's.

You can weld the mounts you need on any axle housing.

[Tx Firefighter]

I've put several 73-87 rear ends in these old coil spring trucks. ECE sells the weld on axle saddles. These in conjunction with a super track bar in place of the panhard bar and you're all set.

The advantages are same wheel bolt pattern, proper width, and a large selection of ratios. Many of these trucks came with 2.73, 3.08, or 3.40 gears.

[nightmare]

Originally Posted by Bus Ted Knuckle

You can weld the mounts you need on any axle housing.

Originally Posted by Tx Firefighter

I've put several 73-87 rear ends in these old coil spring trucks. ECE sells the weld on axle saddles. These in conjunction with a super track bar in place of the panhard bar and you're all set.

The advantages are same wheel bolt pattern, proper width, and a large selection of ratios. Many of these trucks came with 2.73, 3.08, or 3.40 gears.

correct. all i'm saying though is to find an axle out of a totally different vehicle, that will just bolt right in, is almost impossible. anything is possible with a welder.

[jorgensensc]

Originally Posted by LuckyHenriksen

Can't you just find a rear end out of the same year of truck but with 3:08 gearing?

Sounds good, unfortunately there isn't a boat load of these trucks laying around (at least in this area) that have good rear ends and trying to find the right gear ratio. Not to mention 33 + year old parts like to brake.

If it were me i would measure the rear width and hit up a junkyard to find a newer rear, then just buy the correct saddles and weld them on (or have them welded on). You might even be able to get a rear disc brake setup too. Yours is 5 lug right? If it was 6 lug the newer rear ends are aplenty.
Shawn

[jholley]

I have a 3.08 Posi in my 69 that I'm probably going to be getting rid of soon if you're interested. I just scored a 4.11 Detroit Locker that I'm going to use.

[67ChevyRedneck]

What gear ratio do you have now?

[2bits]

I have a 73-87 Axle on mine, running 2.73's and it has plenty of power and I like the highway gears, I am not a racer. Yes it is NOT a bolt in set up, you need to weld the new axle saddles on and grid off the leaf spring saddles and shock mounts. Just make sure the axle is the right length. You might have to get an aftermarket trackbar if the new rear end doesn't have the mount for it too. Not that hard depending on what tools you have and how bad you want it. I had to do mine. Probably a better idea to take the existing axle housing and swap out the gears for you.

[chevy_mike]

Originally Posted by Tx Firefighter

I've put several 73-87 rear ends in these old coil spring trucks. ECE sells the weld on axle saddles. These in conjunction with a super track bar in place of the panhard bar and you're all set.

The advantages are same wheel bolt pattern, proper width, and a large selection of ratios. Many of these trucks came with 2.73, 3.08, or 3.40 gears.

This is exactly what I am doing with mine. I have a rear end from a '74 with 3.40 gears, already cut and ground the old mounts off and after I clean up my trailing arms, I will put it in with the ECE saddles and super track bar. Nice thing is that it's 1.5" wider then my '68 so it will match the track width when I put the disc brakes up front.

I am also putting discs on the rear too.

[Tx Firefighter]

Bobcat ?

[BigSky71]

Fwiw its worth my truck gets the same mileage with the stock 3.55s as it does with my now 2.75s, mind you this is about 1/3 highway and 2/3 driving around town.

I think you will need to do a fair amount of highway driving for the cost of the rearend change to work out savings wise.

[67ChevyRedneck]

^Did you fix/adjust your speedometer/odometer?

[El Jay]

Originally Posted by BigSky71

Fwiw its worth my truck gets the same mileage with the stock 3.55s as it does with my now 2.75s, mind you this is about 1/3 highway and 2/3 driving around town.

I think you will need to do a fair amount of highway driving for the cost of the rearend change to work out savings wise.

My uncle says the same thing about his C-30 with the GearVendors OD.
It's probably got a lot to do with pushing a 4000 lb. sled with the aerodynamics of a barn.

But you're both saving wear & tear on your engines/drive trains.

[69gumby]

I just finnished swapping out the rear end in my 69. I had 4.57 gears and found a rear end at the wrecking yard from 70 that had 3.07 gears. After cleaning and painting and installing I have come to the conclusion it would have been easier, but a little more expensive, to just go to a rear end shop and had the gears I wanted installed. While I am happy with the job I did and the way she drives I still have old used parts, if I would have gone the other way they would all be brand new.

[2bits]

[QUOTE=Tx Firefighter;2981681]Bobcat ?

QUOTE]

hmm his name is Jerrod, if that's what your asking

[Tx Firefighter]

[quote=2bits;2981830]

Originally Posted by Tx Firefighter

Bobcat ?

QUOTE]

hmm his name is Jerrod, if that's what your asking

No, the welder you knucklehead . It's either a Bobcat, Trailblazer, or a Legend. I was wondering which. I'm a bobcat man myself.

[oldblue1968chevy]

I dunno which gears i have

and so yall think its easier/beter spent money to take it to a rear end shop (where would i find one of those, or is that what there called lol) and have them put the gears in it id want?

and what gears would i want mostly driving around town and some 4lane highway miles...prob not alot of interestate miles though...

THANKS!

[BigSky71]

Originally Posted by 67ChevyRedneck

^Did you fix/adjust your speedometer/odometer?

No I didn't and that is a good point, I am not counting the actual miles driven. The difference between 3.55 and 2.75 is 22.5%, hmm maybe I am getting better mileage than I thought .

So my mileage with the 2.75s is about 14 instead of 11.5. My 350 is fresh, mild cam, Edelbrock carb, headers, and a TH350, fwiw...

[oldblue1968chevy]

..so what gears are best for me...and how much $ is this gonna run..and which is gona give beter gas mileage..different tranny th350 or similar or re gear the diff. ? thanks again

[ratpackv8sonly]

New gears and a tranny. Go with a 700R4. But get someone that knows them to install the wiring for the overdrive. I know alot of people dont like them but a new reman stock Q-jet will help out with the gas milage.

[69gumby]

I started a thread a few days ago titled 12 bolt gear ratio. In that thread I posted some rear end ratio codes. You can find the code on the top of your passenger side axle tube. Check that out and maybe you can find out what you have now, if the gears you have now are the ones that came with your truck, then you may have an idea of where you want to go. The previous owner of my truck had installed 4.57s. My truck has a 350 / th350 and I am liking the 3.07s I just installed. I drive 75% freeway and 25% street and I have noticed an improvement in my milage right away. My truck still gets of the line pretty good but also cruses at 70 without straining.