Posi/LSD Part Number?

[81Cheyenne]

What is the part number for the Posi unit that I need for my 81 C10 2WD with a 10 bolt rear end?  According to what I've read, I believe that I need a 8.5" 28 spline unit. Is this correct?

[team39763]

Yeah, I'm pretty sure those are the correct specs.  Are you looking for a GM Posi(Gov Lock)? or an aftermarket like Eaton or Detroit Tru-trac?  I think Summit carries about 5 different units for our trucks, so you might want to check there.

[81Cheyenne]

Nope. I'm not wanting a Gov-Loc. I'm looking for the part number(s) for a limited slip unit.

[Captkaos]

A Gov-Loc is a limited slip unit.  I am guessing you are looking for any other type of limited slip.
Can't really give you part numbers as it depends on the gear ratio/carrier size, but if you call any reputable shop with what you have they can get you the part.  I generally deal with randysringandpinion.com

[81Cheyenne]

Maybe I should have been more specific. I'm wanting the type that does not have a locking mechanism which is actuated by centrifugal force. The kind with the springs and clutch surfaces. Isn't that the type used on this year truck?

[VileZambonie]

http://store.summitracing.com/partdetail.asp?autofilter=1&part=ETN%2D19557%2D010&N=700+400133+304042+4294908216+4294925046+4294791217+115&autoview=sku

[81Cheyenne]

Yep. that would be the one.  Did GM originally use the Eaton?  If so, did it have the same part number?

[Captkaos]

Post 79ish GM switched to the Gov-loc instead of the Clutch LSD.  They were all option G80 even today...

[81Cheyenne]

Considering what I am wanting to use it for, (81 LWB 2WD 383 TBI or carb, used for pulling a boat with a slide in camper) is one batter than the other?

[Captkaos]

Based on that application, the Gov-loc.

[81Cheyenne]

How does the Gov-loc work differently than a clutch type LSD?  What applications would a LSD be better suited for?

[Captkaos]

When it senses slip it locks the axles together, the Clutch LSD never locks.

[Blue 82]

G80 = Gov-Lock
I like the gov-lock
I have the G-80 in my Suburban and my 2000 Tahoe Limited,
but I prefer the Camaro type clutch posi in my 82 at slippery boat ramps
Just a personal preference, the clutch type has never failed me at the ramp, I've had a couple close calls with the Gov-Lock - example: one tire spins causing rearward motion, the the other tire locks and spins while still sliding rearwards.... While an 800 lb flats boat is easy to stop with the brakes, a 26' Dusky with a Big Block under the center console is another story. I'm at the ramp 75 to 100 times a year, the clutch type works better for me to "ease" up the ramp. (you'll see what I mean, if you look at the last 10 seconds of the last video)

here's a video on how the gov-lock works

http://www.youtube.com/watch?v=KbMZ9vcYVSg

G80 in action

http://www.youtube.com/watch?v=-vgblN-2aZ0&feature=related

http://www.youtube.com/watch?v=p8nAbg5suFw&feature=related

[Captkaos]

G80 was GM's RPO designation for all limited slips, from the previous clutch type to the current Gov-loc.

[SUX2BU99]

That vid of the G80 computer animation was cool. I love mechanical engineering   

I had what I would guess is the G80 in my bone stock 81 Jimmy 2wd (my first vehicle). I remember it clunking away when one tire would lose traction (only in the snow or ice, since the 305 2bbl sure wouldn't burn rubber) or if it was really really cold out and driving it 1st thign in the morning.