10 bolt vs 12 bolt

whats the big diff between a 10 and 12 bolt? which one is stronger and how do they compare to a dana 44?  
solid axle chevys cant be beat
78 K5: 350 V8,700r4,np208, 8 lug D44 4:88, 14 bolt 10.5 4:88 with detroit locker and 35 inc parenelli jones dirt grip tires

There is actually two twelve bolts and two 10 bolts. On the 12 bolts there is a 12 bolt car which has a 1.625 diameter pinion shaft and 12 bolt truck which has only a 1.438 pinion shaft. (it is possible to use car gears in a truck 12 bolt if you change pinion bearings) It got its name from the fact that 12ea 3/8 inch bolts hold ring gear to carrier and 12 bolts holding cover on. On the 10 bolt 8.5 inch ring gear size there was the original 10 bolt that had a 1.625 pinion shaft diameter and 10ea 7/16 inch bolts holding it on and then between 89 and 91 GM upgraded it and called it a 10 bolt 8.6 (gears will interchange with old 8.5) During those year it was possible to get either axle. This new 10 bolt has axle shafts that are .100 inch bigger in diameter which make them a stronger than old ones and it uses same number and size of bolts holding ring gear on. (both 10 and 12 bolt are 30 spline) The D44 also comes in two versions, The original and most common one has a 1.375 inch diameter 26 spline pinion shaft and 10ea 3/8 inch bolts on 8.5 inch ring gear. The D44 used in Vette, Viper and some Grand Cherokee rear axles have a 1.625 29 spline pinion shaft and 10ea 3/8 inch bolts too. I would have to place a modern 10 bolt above a old 12 bolt, especailly in truck version and old 12 bolt car about equal to it. If I had to choose between a modern 10 bolt, a 12 bolt and a D44 for a rear axle, I would likely choose the 10 modern bolt. (Excluding Vette/Viper D44 maybe) If you are looking for a rear axle upgrade I would suggest you look for a 14 bolt 9.5 inch semi floater as it can be had with same 6 lug pattern as 10 bolt and is about the equal of a stock D60 and a big step up from a 10 bolt in axle shaft, pinion, carrier and housing strength. The 9.5 has a 1.875 inch diameter 30 spline pinion shaft and 12 ea 12 mm bolts holding ring gear to carrier (these are just under 1/2 inch in diameter) The cover has 14 bolts on it and is where it got its 14 bolt name but it is also known as the GM 9.5.  Did I help you or confuse you further?  

what do you think about the 14 bolt 10.5 full floater  

The 14bolt 10.5 is one of the most swapped axles out there, right along with the Dana 60 and it can handle quite a bit. It is a very good choice if you are considering big power or big tires.

With that said I'm sure Sno will come in and fill you in on all the technical junk associated with the 14bolt...  
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well that helped but know im bummed becuase i was hoping my 12 bolt rear in my 78 blazer was better than later 10 bolts.  If i do swap out the axle its going to be for a full floating 14 bolt or d60  
solid axle chevys cant be beat
78 K5: 350 V8,700r4,np208, 8 lug D44 4:88, 14 bolt 10.5 4:88 with detroit locker and 35 inc parenelli jones dirt grip tires

I have  the 14 bolt 10.5" full floater.  Its a great rearend but it has low ground clearance,  I mean i have 33x12.5 16.5 and there is maybe a foot of clearance.  All I can say is if you go with the 14 bolt id go with tall tires.  

Most overlook the 14 bolt  9.5 semi floater for 1/2 ton upgrades. It is a big upgrade over a 10 bolt and 33 or 35 are really nothing for it and it weighs less and has better ground clearance too. It is about the equal of a D60 but for some strange reason with many it is 14 bolt full float or nothing. The 9.5 has no carrier ratio "break" either when doing gear ratio upgrades while 10.5 does.  

I .have a 98 tahoe 4x4.I just upgraded the rearend gears to 4.56 i still need to do the front.some people say to put the 4.11 on the front due to driving to and from work,wont it bust the gears when i go off-roading?,the reason i had to upgrade was cause when i got it the old owner put 35's when i was going up a hill it would slow me down alot.  

make sure u get macthing gear ratio sets otherwise your going to have some binding problems  
solid axle chevys cant be beat
78 K5: 350 V8,700r4,np208, 8 lug D44 4:88, 14 bolt 10.5 4:88 with detroit locker and 35 inc parenelli jones dirt grip tires

BIGCHEVYMAN:
I .have a 98 tahoe 4x4.I just upgraded the rearend gears to 4.56 i still need to do the front.some people say to put the 4.11 on the front due to driving to and from work,wont it bust the gears when i go off-roading?,the reason i had to upgrade was cause when i got it the old owner put 35's when i was going up a hill it would slow me down alot.

For some reason many are hung up on 4.10 as being the perfect ratio but there is no perfect ratio because what you need is determined by tire size and vehicle, not a universal ratio. In your case a 4.56 was a far better choice than a 4.10 and a 4.88 would have been better still. Even with 4.88's you RPM at a 65 MPH cruise would only be about 2100 RPM in OD. Also as another poster said, you must match front a rear ratios or severe bind in drive line when in 4WD will result.  

yeah,that's what i heard. Gears got to match our it will bust(that's why i have'nt been off-roadin bummer!).. So can some1 give a few tips for more horespower? i have a 350 and basics (intake,spacer,headers,hypertech programmer instaled),91k mls...   oh thanks snoman,geo450racer.  

Well for one thing , a throttle valve spacer is a total waster of money with VorTec engines. It helps some with TBI but not with a multipoint injected VorTec. Next big tip is to NOT use 87 octane ever. Use at least 89 octane with 91 or higher in summer even better. (this can help alot) That engine uses a advanced knock control system and it will not knock on 87 when working but it controls it by retarding spark which reduces power and efficency. BTW, I own a 350 VorTec in a 2000 K3500 SRW which I bought new and it is still older style (there was no Silverado K3500's until 2001)so I know the engine well. I never feed mine 87 now and have not since shortly after I got it as it runs so much better on 89 or better fuel. My truck is stock except for a hypertech tune and has stock size tires and is used for towing and plowing snow. I like hypertech tune because you can get speedo dead on with it.  Another thing, headers will hurt not help lower RPM torque and response as well dual exhausts. (it has to do with letting expanding gasses which drive piston down escape too quickly at lower RPM's) Unless you drive with foot in floor and wind it out to max RPM all the time you are better off with a custom large single exhaust. One more thing, a good after market intake can get you a few extra ponies because the 350 VorTec lacks a true tuned intake like 4.8, 5.3 and 6.0's have.  

What is a "carrier ratio break" and how does this affect the 10.5?  
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Carrier break is were because of ring gear thickness the carriers' flange on which the ring gear mounts on is spaced on a different center relative to pinion center. (the deeper the axle ratio, the smaller the pinion gear diameter and the thicker the ring gear) 10.5 14 bolts have a break at 4.10/4.56. (at 4.10 and below you use one carrier and 4.56 and above you use another with standard thickness factory gears) With a 10.5 though you can get what we call after market "thick" gears of good quality so it is possible to use a 4.10 carrier with 4.56, 4.88, 5.13 and 5.38 gears. It is not possible to use a 4.56 carrier with gears below 4.56. Axles like Dana's generally do not have option of thick gears so you have to basically use one carrier at 3.73 and below and another at 3.92 and above. Did I answer your question?  

So if i have to re-gear for larger tires, my choices are limited to 4.56 and up?  
it pays to be a winner