1986 C10 GU2 rear end

[swilliams]

I have the stock GU2 rear end in my 1986 C10. I need to find out if it has 28 or 30 spline axles. What i have found says it depends on the year but does not go any farther. Thanks

[Stewart G Griffin]

i think up to 87, the axles were 28. (77-87)  After 88 they went to 30.  But if you get a 30 spline carrier the 30 spline axles from later 10 bolts and 12 bolt trucks can fit.

This is according to Randy's differential book.

They are a top notch shop.  i would suggest calling them for help. :
 http://www.ringpinion.com/

[swilliams]

Thanks for the help

[Captkaos]

The newer axles from a 88-up C/K 10 bolt are longer than 87 down R/V and C/K 10 bolts.

[swilliams]

This is what i am looking at going with Detroit Locker 912A556 Detroit Truetrac Differential. It is for 28 spline axles. I want to be sure i  don't have 30 spline.

[Stewart G Griffin]

The newer axles from a 88-up C/K 10 bolt are longer than 87 down R/V and C/K 10 bolts.

i'm sorry i meant the 12 bolt 30 spline axles which originally came in a 73-81 truck.

[swilliams]

Thanks for the help.

[78BIG-TEN]

I used a True Trac and it crapped out in just over a year,worm gears inside gave up,but I think they might have upgraded these units.It was on a 89 k1500 with 33x10.50 tires.It made a horrific noise in tight turns

[swilliams]

What would be a better choice?

[Captkaos]

Some 12bolt 30 splines may require some massagine to get them to work, but yest they will go in.
As for a limited slip, it is going to come down to an individuals preference. 
I used Eaton Clutch type LSD,  I know of people using the newer Truetrack without issues

What is the intended purpose?

[78BIG-TEN]

I like the Eaton clutch type as well,that is what I replaced the True Trac with and some 7 years later still going,

[Stewart G Griffin]

Thanks for the help.

No problem.

And i wonder if the 88-91 blazers and suburbans had the 30 spline axles?

[swilliams]

My purpose is that since i have done some upgrades I spin the one tire. I am thinking that posi will help cut down on the tire spin.

[Captkaos]

And i wonder if the 88-91 blazers and suburbans had the 30 spline axles?

Yes they did...

It could make it spin both, but it should help...

[Rich84]

I used a 30spline carrier and axles out of an 88 and up truck in my 10 bolt..If I remember correctly the axles were about 3/8 of an inch longer. I had to go with a Buick Roadmaster drum to accommodate the longer axle.