for those that want something stronger than a 6 lug 10bolt

this converts a 10.5" 14bolt to a six lug
http://www.tomsdifferentials.com/cat129.htm

 

or......you could just salvage one out of an '88-'98 Z71 with a towing package.....they COME with the 10.5" SF 6-lug 14 bolt

 

Well, no, not actually. There never was a 10.5" 6-lug rear. All 10.5" are full-floater 8-lug.
The 9.5" 14-bolt semi-float rear is the one you are thinking of. They came in smallblock 2500 and heavy half-ton old-body-style trucks in both 6 and 8 lug versions. In the 454SS the 9.5" came in the only 5-lug application for that axle. In NBS trucks all 9.5" rears are 8-lug.

I run a 10.5" rear converted to semi-float (but no c-clips) with 5-lug axles. It's strong enough to get the front wheels off the ground and hasn't given me a bit of trouble with 4.56 gears and an Eaton Posi. VERY strong unit.

 

Seems to me like a few members could use or will soon need something stronger than the 10bolt.

 

My fault...I MEANT to type 9.5", and that 9.5" SF rear is more than strong enough to handle most anything yo want to throw at it

 

Reading for your pleasure:

"We had to dump the Project truck's original half-ton 10-bolt rear axle. The 8-½" diameter ring gear and 1330 U-joint pinion yoke were deemed not up to the task when twisted by a Duramax 6600 producing more than 600-horsepower and 900 lb-ft of torque. Without going the custom (expensive) route for a stronger replacement, we chose the GM 9-½ 14-bolt semi-floater for this six-lug application. Once acquiring the axle, we visited the experts at Randy's Ring & Pinion for a professional rebuild.

According to automotive writer and 4x4 guru Jim Allen, the GM 9½ has a short-term output torque rating of just under 5,000 lbs-ft (vs 3,800 for the 10-bolt it replaced) and a max continuous torque rating somewhere around 1500 lbs-ft. Jim went on to say that, "In theory, a built Duramax with its massive torque multiplied by the gears will generate way more torque than that, but thank God for imperfect traction. Tire grip can be calculated, but you'd need the exact weight on the rear tires (including some extra for weight transfer from acceleration) and the rear tire radius. I calculated it roughly, getting rear weight data from a similar year Sportside truck, plugged it into the formula and found that it only would take about 260 lbs-ft of engine torque (3,000 lbs-ft as multiplied by the drivetrain) to slip your tires on pavement, figuring 2400 pounds on the rear tires (2,200 plus 10 percent for acceleration transfer) and the friction coefficient of average pavement (.8). With more weight, you'd get a higher number... and better acceleration."

Jim Allen continues, "Your maximum torque multiplication comes from multiplying the engine torque by the first gear ratio, and rear axle ratio. Using the stock Duramax torque, that would be 6,475 lbs-ft in high range and 17,480 lbs-ft in 4WD low range. As long as your traction torque doesn't get to close to the maximum capacity of the axle, you are OK. Given all the variables, you are uncomfortably close with the 10-bolt. You have an extra 1,200 lbs-ft of cushion with the 14-bolt. BTW, the 10.5 axle is rated for 6242 lbs-ft and the new 11.5 inch unit found in the 2500HD/3500 is rated for 8321 lbs-ft."

 

This guy makes new hubs for the full floater 60's, that convert them to 6 lug.

www.gradysoffroad.com

 

I have a set of grady's hubs on my 10.5" 14 bolt. So I know have a 6 lug full floater. I installed it in my blazer. I didnt want to deal with finding a dana 60 for my front end so I converted my rear to 6 lug. Im really happy with it. The diff must have lost at least 150 lbs when I did this. His hubs are billet and you convert to disk brakes at the same time so there is definately a weight reduction.

I doubt anyone here needs a diff that strong, but if someone wanted to go that route the end result is nice. and you do get a full floater rear end.

 

10.5 is a very tough rear. We sell a lot of parts for them, but usually due to aging and wear. Big strong rear, and easy to work on. Also, since it is a full floating axle the hafts only deal with rotational stresses, no the stress of the weight of the vehicle.

 

where do you work?