12 bolt rear axle vs 10 bolt?

[Gearhead1]

I just picked up a 12 bolt post from a late 70's C10. Its condition is unknown, but my 10 bolt posi is toast. I understand that these truck 12 bolt axles are not nearly as good as the late 60's-early 70's Hi-po car axles. Can anyone give me the basic lowdown on the truck versions? Good/bad/ugly?
I assume its still a better rebuild candidate than my '87 10 bolt axle?
Is there anything special about them?

thanks in advance
 

[pholliday1]

The big thing is what are your plans for it? If lifted tires, high horse power is your answer than thats probably not the right axle for you(either 10 or 12 bolt) however it your plans are mild and it sounds like low buck is the key here then generally in a situation like that you ask your self which parts are most common (therefore cheaper) my guess is the 10 bolt. I'm not going to bore you with spring perch widths shock mounts and pinion angles or spline count. Just take a look at the big picture so your not going through the process again in one year.

[Gearhead1]

Thanks - my truck is a SWB R10 - will be used for daily driving and the odd bit of fun on the loud pedal when I build a better motor. Thinking 400hp/450 lbs torque at the very most, but more realistically something along the lines of 325/375ish.
There may be some towing involved up to 5500 lbs max.

When you say spring perch, shock mounts, pinion angles...isn't a '79 axle a direct bolt in to an 87? I thought the 12 bolt was an option up to 87...

[Blazin]

It is a direct swap except you will need a cross over u joint. the 12 bolt u joint cross is a bit smaller, and the caps are a bit smaller than a 10  bolts joint. I believe 79 was the last year 12 bolts were offered in our trucks. As far as strength goes, the 12 bolt is  pretty much the same. If it is stronger its is a very minimal amount.

[Captkaos]

12 bolts were still being depleted until 1981.  The difference in them is the 10 bolt has a bigger stronger pinion gear, the 12 bolt has a larger ring gear.   A 12 bolt truck is nothing like a 12 bolt passenger car, the car has a larger pinion gear.
In comparison, you are neither gaining or losing in the switch if you are putting HUGE mudders on there.

[Gearhead1]

Thanks again - no mudders, this is a street truck - 2wd wi/ 15" rims