Rearends

[Andyboy]

I know this is probably here somewhere but can't find it. I was told I can put a 71 or 72 half ton rearend in my 68 c20 spring rear. Is this true and how much work is this? what is the ratio on the 71-72 rearends?

[stsalvage]

Now i have a 1968 3/4 ton longhorn I'm thinking of doing that too.But i have leaf springs.Now the one main Problem with the 1971--72 12 bolts with coil springs is every one wants coils and the price of a coil spring rear ends out here in Calif are 400 to $500.00 But the leaf springs dime a dozen.

The change over is Nothing bad at all Before.You put the rear end in.When you find it and buy it.Open it up check the gears.Put 2 jack stands under t rear end and have a friend help you.Put tires on the rear end and count how many times the pinion gear shaft turns that where you get what gear ratio in the rear end But if your lucky and you take the rear end out of the truck its in.Check the glove box door it should tell ya most 1/2 with automatics had 3.73 gear Now sticks might be high or lower

the change over things you might want to do be for you stick it in

1# check the rear gears check for broken gears or cracks

2# pinion seal if its oily means it needs a new seal Best off if you buy one have a friend that knows something about rear ends and look in it before you buy it.

3# brake drums and brakes get them done before you put it in Clean the rear end and paint it if the rear end is good Put a new Seal on the diff cover and a new seal.

Now the 3/4 ton and 1/2 drive lines should be the same but if not But 1 u joint for the back drive shaft

your E brake cables are the same when you pull out the axles check for any damage

One thing most street rodders do when they buy a used rear end and put it together and after they do all the stuff to it.Later they tell me they have to go back in and do it Is Change to new wheel studs after 50 years or in are case 35 years of use them lug nuts and studs are pretty used up better off having new

4# your rear brake lines and rubber hose in the back best off change every thing to new never take a chance with brakes

Something most guys that work on car's and trucks for a living Rotors and drums even tho there new there not straight and there not even best thing to do with new drums and rotors is take them to a shop that has a brake lathe and have them turned down once before you put them on.

The seating prosses is shorter time and man they will put you throw the windshield so much more better barking from other then that

One thing i for got the rear coil springs they have 4 different types

1 is stock 1/2

2 is 3/4 ton and 1 ton

3 is lowered cut down 2 inch 3 inch and so on

sence its a coil spring and not a leaf spring and you do any hauling best off to use the 3/4 ton and see if you like the feel if not change to 1/2 ton

[dave2953]

Originally Posted by Andyboy

I know this is probably here somewhere but can't find it. I was told I can put a 71 or 72 half ton rearend in my 68 c20 spring rear. Is this true and how much work is this? what is the ratio on the 71-72 rearends?

As stated above, the ratios varied. When you say your C20 is a spring rear, do you mean coil or leaf?

[Longhorn Man]

if you have coils, then it is as easy as unbolting the u bolts, remove the rearend, slapping the new rear in there, and hooking it up. I used the rear drive shaft from a 1/2 ton and slid it right onto my 3/4 ton front shaft. (i went dana to 12 bolt)

[Longhorn Man]

almost left out, 3.07 was used in small block/auto and 4 speeds (options were avalible and should be on spid) and 3.73 was used in 3 speed trucks, again options avalible.
There was a 4.10 used on overdrive trucks, and there's a couple deviations from thses rules, but that's the general rule

[Andyboy]

Thanks stsalvage for the all the details. I guess I have to look for a 12 bolt and spend some money, but I think I will be better off. Thanks again.

Dave2953 I have coils.

Thanks longhorn man I hope It's that easy.

Thanks again guys.

[Longhorn Man]

it is that easy, did it on my burb.
Plan on cutting the U bolts

[treveiger]

x2 on cutting the U bolts, and when you do the first cut on each side remember there under pressure so expect a POP noise when your getting close to cutting through or you might end up banging your head on the back wheel well pretty good. ask me how i know