1/2 ton axle question

[82 Silverado 4X]

My 82 has what I remember to be 2:73 gears when I checked a few years ago. They are quite lame for my area's terrain even with the 350. Now that I have the body and interior done I'm considering swaping in some new housings with deeper gears. I want the swap to be quick with no glitches. Besides other 80's trucks with SM465's trans and NP208 transfer case, what other years/models will bolt right in without mods to the yokes and driveshaft's? Will the housings from late 70's trucks with TH350 and NP203 bolt in? I just don't want to mess with cutting driveshafts and changing yokes.
Thanks

[tornado_tech]

Any GM product 73-87 1/2 ton front or rear will bolt in with no adjustment needed to driveshafts or yokes. The 3/4 tons front is also a direct bolt in but the rear end will require a U-joint change.

[82 Silverado 4X]

Thanks for the quick answer. At one time I considered changing over to 3/4 ton but over the past couple years I have accumulated 3 extra sets of 15" tires already on wheels for the 6 bolt axles. Also the truck rarely sees any off-road duty and never hauls or tows anything heavy. I really didn't want to get into the expense of gear changes and the cost of getting them set up. That's why my plan is to get a set of good complete front and rear differentials and replace everything that's worn or needs replaced ( seals, bearings, balljoints, brakeparts and axel lube) before installing them in the truck.
One other thing, my 77 Blazer Chalet has the NP 203 Full-Time. The front axle just has a chrome cap cover that appears to just push in. My 82 front axle has automatic hubs with covers that bolt on with allen screws. Do the late 70's front axles have the provisions for using my 82's automatic hub covers?

[LONGHAIR]

Yea they do. You are right about your "full-time" cover just pushing in, but the gear inside is held in place by two snap-rings. A little one on the axle itself and a larger one that is in a groove in the hub. It will be buryed in grease, but it is there. That same groove will hold in your new hubs.
I would recommend that you change to a set of manual locking hubs though. Those automatics never were very good when they were new...........now they are over 20 years old. I wouldn't trust them, but they will fit in there. Also,you have to take the outer wheel bearing nut and the retaining washer from the truck with the automatics and switch them into the other axle to make the automatics work. Those 4 tabs on that washer are required for the automatics, but none of the other hub styles use them.

[82 Silverado 4X]

Thanks Longhair
Sounds great. My auto hubs on my 82 have never failed me in 3 years of use and I would really like to keep the change-over as stock looking and functioning as possible. New differentials with 3.73 gears would make my truck perfect for the type of driving I do with it.

[82 Silverado 4X]

OK, I just left my freind's boneyard. I mentioned that I was looking for a matched set of housings with deeper gears. He said he thought that the 79 Blazer that I got my tach cluster from had 3.73's but I would have to check the ratio for myself. I immediately saw that it has a 12 bolt in the rear. Upon opening the case I found that it has a governor-lock with 41-ring teeth and 11-pinion teeth which is a 3.73 gear.
I currently have a 10 bolt with an Auburn Limited Slip and 2:73's in my truck. Is the 12 bolt a stronger housing? Are the governor-locks any good?
Here's a couple of pics.

[LONGHAIR]

Gov-locs are generally considered boat-anchors. They are known to be weak. The small springs, gear teeth and "locking device" break and get loose in the housing. Those small parts are really rough on the ring & pinion as well as the bearings.
There are those who belive these units to be somewhat servicable......but only with stock sized tires and stock engines. Any high performance parts or larger tires will definately kill it.

[82 Silverado 4X]

Thanks again LONGHAIR. Yea, I'm sure it would ruin my day to have chunks of metal meshing with the ring and pinion. I have a stock 350 and have 31" tires. It's my winter work truck. I don't do off road and only really want a posi-type so I don't need to pull it in 4wd everytime I come up my driveway in the winter. For this type of use, do you think it's strong enough?

[LONGHAIR]

As long as you are "aware" that it is a potential weak link........and treat it as such, you should be ok. Just be nice to it.

The bad part of those things is the "thinking" behind the design. They are "supposed to" allow normal open-type differential action up to a certain point. I have always heard that it was around 20%. Meaning that if one wheel was spinning more than 20% faster than the other it would enguage. This is a based on the little gears and centrifugal force of the locking mechanism. This was also supposed to disable the locking above a certain axle RPM (somewhere around 35mph depending upon tire diameter) which is fine, you shouldn't need posi at that speed during street driving/ mild off-roading.
The idea it is all based on is ok........the little parts are just to "fiddley" to be in a rear end that gets any real use. Stock motor, near stock sized tires, awareness of the weak link, you can probably get by. It might be good insurance to make taking the cover off and looking inside part of you regular maintenance. I would think that yearly inspection should be good enough, unless you have some reason to think you might have hurt it before the next time comes up.

[82 Silverado 4X]

Thanks again LONGHAIR. I quit beating on things and using them to extremes about 20 years ago. I don't enjoy laying under and working on things like I used to, so I can honestly say, "if it breaks, something must have been faulty to begin with".
You are correct on your description behind the design. I have a GM Unit Repair Manual that covers all the axels and how to repair them . I read the section on testing the governor-lock's and will be doing that before I remove it from the Blazer. I'm getting the differentials for nothing so all I have to lose is my time.

[LONGHAIR]

No problem, that's what we are here for. I certainly wasn't trying to tell you not to use it, just be aware of it's limitations. I'm sure that there are still millions of them out there still running....and probably just as many that are broken and still being driven too People tend to forget about the rear axle, it is just down there for the life of the vehicle.

[badpeanut]

Just to share my experience with a Gov-lock: I had a '87 2-wheel drive w/2.73 gears. When I bought the truck it had P235R75/15 tires. The Gov-lok worked well with this combination. Shortly after I went to P255R70/15 tires I was turning around in a fresh asphalt parking lot at about 15mph when it started clunking and poping. When I got it home I took off the cover and there was a piece of the little "Swiss watch" Gov-lock gear in the bottom. It was high mileage and maybe the previous owner abused it (not that I knew), but I took care of it.

Since yours is free use it and enjoy it until it breaks.

[Zoomad75]

Going with the 12 bolt over your 10 won't net a whole lot of addtional strength, case wise or with the gearset. But for a stock drivetrain with 31" tires it should be more than capable.

Going with that gearing combined with your tire size is going to give you 2 things. Increased power (which you were looking for) but also higher operating RPMs when driving on the highway. 3.73's with 31's (465 also) is how my K5 came to me. 65 mph came in at around 2,600 rpm. 75 mph brought the rpms up to 3,000. The higher rpm won't kill it but it will put a good dent in your wallet for fuel economy. It's a trade off for sure, just be aware of it.

Gov-locks are strange in how they operate. Longhair explained well how they work. Low speeds only and at about a 100 rpm difference from one side to another. They engage with a bang or a pop. To me thats what kills them. To go from a 100 rpm difference or more and then to fully locked in an instant can't be good on parts. No clutch to slip, just instant action. Which, if you are on a soft surface like dirt or snow, the gov lock action should be fine due to the low traction. It's different on a high traction surface like dry roads and what not. Turning a corner and hammering on the throttle might be your worst enemy to the gov lock. Turning forces the difference of speed and adding addtional slippage by hammering the throttle will spin the inside tire (more difference in speed). Straighten out from the corner on the throttle and bang. Down goes the gov-lock. I won't say it will happen the first time out, but repeated beatings on the gov-lock internal parts will cause an early failure.

Trust me the new found power you will have moving from 2.73's to 3.73's will have you jumping all over the throttle, just take it easy on the corners and you gov-lock should give you decent service.

[82 Silverado 4X]

Thank you both for your input on the gov-lok weaknesses.
I live in an area that level roads are hard to find and hills are the norm. Winter snow driving is the primary use of my truck. At 10-12 MPG, using it as a daily driver is out of the question. I have a little beater that I use for work in the summer and when the roads are dry. I also have a conversion van that I use when we travel. The last time my truck saw anything over 60MPG it was when it was owned by someone else. I don't do any off-roading.

Which brings up another question:

Will the Auburn Gear Limited Slip that's in my 2.73 geared 10 bolt work in the 3.73 geared 12 bolt housing?

[Zoomad75]

Quick answer, no. 10 and 12 bolt carriers are not interchangeable. There are many dimensional differences between the two, but the biggest is the ring gear diameter. Your 10 bolt is a 8.5" ring gear and the 12 bolt is a 9.5". That right there will stop you from bolting up the 12 bolt 3.73 gear onto your 10 bolt auburn. I'd stick with the gov lock in the 12 bolt for now. If it ever does grenade you would have to get a new carrier anyway. then you can get what ever limited slip you like.

[82 Silverado 4X]

Thanks, If it breaks, I guess I'll just have to bite the bullet and get a shop to install 3.73's in my 10 bolt or find another complete used housing with 3.73's.