this rear axle stuff is confusing, but I have to go posi

[Slowguy]

I think for the time being I’d like to use the 2500 donor truck driveshaft...if that’s a possibility as the cheapest option? It would already fit directly into the 4l80e and I’d need to install the yoke onto the posi 12 bike I’m building now. Hopefully the yoke from the donor rearend fits the 12 bolt? I’ve never removed a yoke but it looks like a bolt and a spline.

I ordered all the stuff we discussed including the trutrac, locking shims, and the rebuild kit from strang. The yoke selection will be the last peice of the puzzle.

[Mike C]

There are some differences with the yokes. Most 12 bolts will have a 1310 u-joint size, but big block 1/2 ton trucks will have 1330.

The 1330 is same diameter cap as the 1310 with a wider cross. The 1350 has the wider cross of the 1330 as well as a larger cap diameter. Most likely the donor truck has 1350 joints already I would think. But you can measure cap diameter and cross length and Google will let you cross reference those things.

So yes, you can use the 2500 driveshaft after it has been shortened and balanced. I am assuming it is a one piece shaft. I know you can buy 1310-1330 conversion joints but I’m not sure if you can get a 1310-1350 conversion joint. Meaning you may have to buy the yoke for the rear or a different end for the 2500 driveshaft.

[Slowguy]

Should I replace the outer axle bearings at the same time since it appears the axle can easily be pulled out at this time?

[Slowguy]

I'm getting close to getting my body parts back for assembly on the frame. I thought I had my wheel combo figured out but now I've changed my mind again. I need to go with 5 lug axles in the rear. Can anyone tell me what axle I would need to match the stock axles I have in there now? 12 bolt stock 67 axle 3.73 and I changed out the dif to a tru trac as was talked about in earlier part of this thread.

[gmc684x4]

I have looked a bit into 14 bolts companies do make a 6 bolt hub to fit the rear spindle need to turn down the axle hub a bit
Give you a full floater gm diff that can take a lot of abuse

Lots of great advice on 4l80e and gear ratios i have a non posi 3.73 diff 4 series posi i might drive it as is at first see how i like the highway rpms before I drop in the posi might look for a set of 3.42s not looking to build this into a burn out truck getting to old to get caught doing donuts on main Street

[Mike C]

Several companies make replacement 5 lug axle shafts and you can buy new drums. Just google for that or search on this board.

On my '69 I swapped a 71-72 housing into the truck which is 3/4" wider on each side. This additional width helped me get the wheel/tire fitment I wanted with 275 55 17 rear tire on a 17x9, 5" backspace wheel.

My truck is an unusual leaf spring, short step Chevy. If you have a fleetside truck, it is not near as critical as you have a TON of space on the inside to work with. Not so on a stepside truck.

[cj847]

Slowguy,

My recommendation on rear gears:
-do not try to set them up yourself. There are a few special tools and it takes a lot of patience to get them right. Bearings need to be pressed on. Also, my axle shop, that sets up tons of axles, will not guarantee that a set of used gears won't whine (ie they have to be set perfectly to the previous pattern). It is not worth your time or trouble (even though it may cost $300-$500 in labor alone).

-the people who set up the gears will let you know if you need wheel bearings. They basically last forever unless overloaded.

-a tru trac is a "limited slip" differential which is probably best for a street truck. You may want to study the difference between it and a true "detroit" locker.

[gmc684x4]

For a true street driven truck you do not want a locker it will have less desirable street manors it is more appropriate for a 4x4 going off road

My first drive home with a Detroit bang bang I got ho.e checked out the intire drive train driving fast through corners will make it look and unlock with a huge bang

[Accelo]

I agree with cj847, don't try this on your own as a first time project.
A lot of special tools are required and will cost you more than having it done.

Dial indicator
15 Inch pound torque wrench.
Foot pound torque wrench.
Hydraulic Press
Method to pull the pinion back through the bearings which have to be in the housing.
Pinion wrench
Large socket for the pinion nut.
A 2' long breaker bar to tighten the nut.
(some claim you can do this with a impact wrench) YOU can't and get it correct.
And some additional tools to get the old bearings off the pinion if you are reusing the pinion.

Unless you are doing more than one differential it will not pay.
Best of luck

[Slowguy]

I have all these tools and did the procedure quite some time ago. I think I set it dang near perfect...but...i guess I'll just have to wait and find that out the hard way.

I suppose I should have started a new thread on this but I was really asking about what 5 lug rear axles to match up with this stuff. I realize I need 5 lug if I want any sort of options with wheel style. I want to make sure I get the right stuff, and, since I have the stock axles in there now, I'm guessing I just need to get a stock axle swap. I can measure everything when I get the axles out. Excited to see the first bit's of paint hit the body. Re-motivated now I guess you could say!