10 bolt to 12 bolt swap - ?

[Timber]

My 79 2wd K5 has the small 10 bolt rear. I was talking to a friend tonight and found out another friend is parting out his 74 C10 2wd with the 12-bolt.

Will it bolt in my truck with no modifications?

[Blazin]

You will need a cross over u joint. The 12 bolts use a u joint with smaller caps, and a smaller cross.
 The brakes are different diameter and width too. You will be fine if you use the 12 bolt brake parts.

[Captkaos]

You aren't gaining anything doing the swap though.

[Timber]

Why not?

[Blazin]

Because the ten and twelve bolts are really about  the same as far as strength etc.

[VileZambonie]

We could debate this subject forever but I can tell you I've broken more 10's than 12's. But I wouldn't bother with the swap without a good reason either.

[Blazin]

I agree. I too have broken alot more ten bolts than twelve, but I have broke quite a few 12 bolts too.

[Captkaos]

I agree it is a touchy subject, but I think we can all agree that
a) if you are running a stock truck the swap is wasting time/money
b) If you are wheeling on one really hard either have the potential to break.  If you broke a 10 and have a 12 to replace it, no biggie. but I wouldn't buy one I would move to a 14bolt.
c) If you are running larger than 33's and are doing what is decribed in b), going to a 12bolt from a 10bolt isn't a big gain, just find a 14bolt.

If you are going for strength and starting with a 10bolt I would move to a 14bolt if I thought I would be putting it through something that would grenade the 10bolt.

[VileZambonie]

Keep in mind if you do that your lug patterns

[Timber]

I was told today it will be mine for free or next to it.  And it has factory posi, perfect for the 4.10's I'd planned on.  The truck is a toy and I'm building it for no other reason than for cruise-ins and fun, and to make it beat cars that shouldn't get spanked by a 79 K5.  The extra strength may be marginal but it's free.  I'll take it.  I appreciate the help.

[Timber]

Keep in mind if you do that your lug patterns

Don't know how I missed that.  2wd 12-bolts aren't 5-lug 5x5?  This is a 2wd truck, not a mudder.

Thanks.

[Bowtieogre]

Keep in mind if you do that your lug patterns

Don't know how I missed that.  2wd 12-bolts aren't 5-lug 5x5?  This is a 2wd truck, not a mudder.

Thanks.

Youre good, the 12 bolt is also 5on5...I think he meant the difference between the 10/12 bolt and the 14 bolt. What gears are in both rear ends? Are either of them posi? That would be a deciding factor for me.